JPS58219736A - Manufacture of relief structure - Google Patents

Abstract

PURPOSE:To obtain a relief structure without performing development by a method wherein a thin film composed of a radiation decaying polymer material is formed on a substrate, and then a desired part of this thin film is irradiated with radiation beams. CONSTITUTION:The thin film composed of an aldehyde polymer wherein two kinds or more of fatty aldehyde mixtures are put in copolymerization with each other is formed on the substrate. The thin film has properties of decay and scatter by the irradiation of radiation beams. Therefore, pattern formation can be performed without using a special development process by irradiating a desire part of the substrate of forming the above mentioned thin film with radiation beams.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a relief structure, and more particularly to an improved method for forming fine patterns applied to semiconductor devices, magnetic bubble memory devices, integrated circuits, etc.

Conventionally, pattern forming methods used to manufacture electronic components such as semiconductor devices, magnetic bubble memory devices, and integrated circuits include:
Methods using photoresists that are sensitive to ultraviolet or visible light have been widely put into practical use, but in recent years, with the aim of increasing the density and integration of semiconductor devices, patterns with a width of 1 am or less have been formed. A method is required.

However, with the above-mentioned methods that use light, it is extremely difficult to accurately form patterns with a width of 1 pm or less due to the unique properties of the light, such as diffraction, scattering, and interference, and at the same time, the yield may also decrease. Remarkably, the above method using light is not suitable for forming a pattern with a width of 1 ym or less.

In response to this, recently, photolithographic techniques that use ultraviolet or visible light to perform microfabrication have been replaced by linkography techniques that use high-energy radiation such as electron beams, X-rays, and ion beams. As a result of this development and research, various materials that are sensitive to the above-mentioned radiation are being studied. Among these, positive radiation-sensitive organic polymer materials that induce a scission reaction in polymer chains by irradiation with radiation, and the irradiated portion becomes soluble in a developer to form a pattern;
For example, poly(methyl methacrylate), poly-(1-butenesulfone), etc. induce a crosslinking reaction when irradiated with radiation, and the irradiated area becomes insoluble in the developer and forms a pattern. High-resolution patterns compared to molecular materials? : Extremely convenient as a resist material for microfabrication. However, the radiation sensitivity of positive resist materials, including the above-mentioned materials, is 1/10 to 1/10 that of negative resist materials.
00, and as a result, the radiation irradiation time required for pattern formation became long, making it impractical.

It should be noted that when positive resist materials such as poly(methyl methacrylate) mentioned above are irradiated with radiation, the main chain cleavage reaction of the polymer chain is induced and the molecular weight decreases, and as a result, the irradiated area is exposed to organic development. It dissolves in a liquid and becomes blocked, and this is used to form a pattern. However, in order to exploit the difference in solubility by utilizing the difference in molecular weight, a large amount of radiation is required, which is one reason why the sensitivity of positive resist materials is low.

Furthermore, when considering the manufacture of semiconductor devices and the like, several resist steps are used. In each resist process, resist is applied, dried, irradiated with light or radiation,
A typical wet process takes several tens of minutes for development. After developing the resist, the next processing step takes even more time, including the time required to move the wafer.
There has been a strong desire in the semiconductor industry for rapid processing and processing methods that use little wet solvents.

The present invention overcomes the above-mentioned drawbacks of the prior art (but does not require a small amount of radiation exposure and a special development process).
It is an object of the present invention to provide a method for manufacturing high-precision relief structures.

In order to achieve the above object, the present inventor conducted various studies on organic polymer materials and development methods that are thought to have radiation sensitivity. We have discovered a method by which a relief structure can be manufactured without using a special development step by forming a thin polymer film on a substrate and irradiating desired portions of the polymer thin film with radiation.

In other words, in the method of the present invention, the irradiated portion disintegrates and scatters due to the amount of radiation irradiated, making it possible to form a pattern without using a special developing step.

The radiation-sensitive polymer materials used in the present invention include:
An aldehyde monopolymer having a polyether type structure is preferable. In general, homopolymers of aliphatic aldehydes have high crystallinity and are poorly soluble in many organic solvents, so they cannot be used as resist materials.

The present inventor conducted intensive research in order to obtain a polymer that can be used as a resist material by improving the solubility of an aldehyde polymer, and as a result, the present invention was obtained as follows.

In other words, an aldehyde copolymer with improved solubility can be produced by anionically polymerizing a mixture of aliphatic aldehydes of 2's or more (for example, Tanaka et al., Kouka, 20, 694). (1963)), using this as a radiation-sensitive organic polymer material to create a relief structure! I discovered that it would be better if I made a knife.

Aliphatic aldehyde monomer 71 used in the present invention is a mixture of two or more aldehyde monomers selected from aliphatic aldehydes such as rogen isitelkyl group, and the above alkyl group Preferably, those having 1 to 8 carbon atoms are preferred.

If the mixture ratio is regulated by the polymer composition.

The composition is selected from a range in which the largest component contained in the copolymer does not exceed 99 mol. However, in order to obtain a copolymer with particularly high solubility, it is desirable that the largest component contained in the copolymer does not exceed 80 mol.

The polymerization catalyst used when obtaining the polymer of the present invention by anionic polymerization includes dimethylaluminum(diphenyl)amide (C)4)tAt-N(CoHs).
Diethylaluminum(diphenyl)amide (Ct
Hs )z Al-N (Ca )ls )t, ethylaluminum bis(diphenyl)amide (Ct Hs
) At-CN(Cs Hs )z )t, ethylzinc (
diphenyl)amide C,H,ZnN (C5Hs)t
-M to ethylmagnesium(diphenyl)amide C7
Examples include, but are not limited to, gN (C5Hs)y. The amount of catalyst is not limited, but it is 0.1 to 5 mol-0 based on the aldehyde monomer mixture.
It is appropriate to add it in proportion.

In carrying out anionic polymerization, it is not necessary to use a polymerization medium, but if necessary, it is preferable to use a hydrocarbon-based solvent such as toluene or an ethyl ether-based solvent.

Further, the polymerization can be carried out at a temperature in the range of 0°C to -100°C, but a temperature of 150°C to -80°C is usually suitable. Furthermore, the atmosphere for polymerization is preferably one in which the air in the vessel is sufficiently replaced with an inert gas such as nitrogen.

In addition, in the present invention, there are no limitations on the technical method of polymerization itself (such as a method in which an aldehyde mixture is prepared under reduced pressure distillation on a catalyst dissolved in an inert organic solvent, a method in which the aldehyde itself or a solution thereof is Any method may be used, such as adding the catalyst itself or a solution thereof.

When using the radiation-sensitive organic polymer material of the present invention to form a pattern of a semiconductor element, etc., for example,
A solution dissolved in a general-purpose organic solvent such as toluene or xylene is used, and it is usually coated on an element substrate by a spin coating method or a dip coating method. After coating, pre-baking under appropriate temperature conditions, and then irradiating the desired pattern with radiation, the irradiated area collapses and scatters in a chain, resulting in a positive resist pattern being obtained without any development process. be able to. In addition, if necessary, wet development using a toluene-isopropyl alcohol-based organic solvent may be used. When used alone, it is possible to form a resist pattern by radiation irradiation without the need for development processing, but if necessary, it can be used in combination with novolak resin, polyacrylic acid ester polymer, polyisoprene resin, polystyrene, etc. I can't help it. In this case, the drying solution is selected depending on the mixed polymer, and the properties such as #J dry etching properties can be varied.

In addition, the aldehyde polymer of the present invention exhibits high sensitivity to radiation, but is also sensitive to light.
It can also be used as a photosensitive material.

The present invention will be specifically explained below with reference to synthesis examples and examples.

Synthesis example 1 Diethylaluminium diphenylamide.

(C!'4)? ! At N (C5Hs)t was synthesized as follows. After thoroughly purging the inside of a 200 mA four-hole flask with a stirrer, one dropping funnel, a three-way cock, and a thermometer, add toluene: / 55 mA and (CH, CHt)! At1
4. sy (0,127 mol-) was introduced using a syringe through a three-way stopcock under a nitrogen stream. After stirring for a while to make a homogeneous solution, 2t4t (0,127mol) of diphenylamine was added to 40mt of toluene under water cooling.
Gradually add the solution dissolved in After the dropwise addition was completed, the temperature of one reactant was raised to 60°C, and the mixture was gently stirred for 2 hours to complete the reaction. The generated (C!Hs)tAz-
N (c6) (,) was stored as a toluene solution in a container with a three-way cock under a nitrogen stream.

Synthesis examples 2 to 8 Polymerization was carried out using a polymerization tube with a three-way cock.

That is, a predetermined amount of aldehyde monomer and a solvent (usually toluene was used) are introduced into a cylindrical polymerization vessel having a capacity of about 100 mA under a nitrogen stream through a three-way cock using a syringe.

The container containing the 7mer solution is cooled to 0° C. in an ice-water bath, and a predetermined amount of the catalyst solution obtained in Synthesis Example 1 is gradually dropped into the container while vigorously moving the container. After adding the catalyst, the container was cooled to -78° C. in a dry ice-acetone bath, and left to stand for polymerization for a predetermined period of time. After polymerization, the wet product 1 was treated with ammoniacal methanol to decompose the catalyst, and then immersed in methanol for 1 day, separated, washed several times with 1 methanol, and vacuum-dried. In addition, in some cases, the monomer solution was added to the catalyst solution to perform polymerization.

It was determined by analyzing the composition of gas produced by analysis or thermal analysis.

(Table 1) Polymerization time: 24 hours, total monomer amount: 100mm0L
, Solvent: Toluene 1 Total volume of reaction mixture: 27 ml, Initiator CC*Hs) t'' (C5Hs) 1 m 0.1
8 m mob monomer abbreviations AA: acetaldehyde BA nibutyraldehyde PA nibrobanal PhPA: 5-phenylpropanal H human=heptanal IBA: inbutyraldehyde Example 1 The copolymer of acetaldehyde and butyraldehyde obtained in Synthesis Example 2 was It was dissolved in xylene to prepare a 0.2% by weight resist solution. Subsequently, the above resist solution was applied onto a silicon wafer and prebaked at 80° C. for 20 minutes to form a polymer film with a thickness of 15 βm. This was placed in an electron beam irradiation device, and irradiation was performed in vacuum with an electron beam at an acceleration voltage of 20 KV, with different irradiation doses depending on the location.

As a result, the film of the irradiated area was removed without any development treatment, and the thickness of the remaining polymer film was measured using a thin film level difference meter at the areas irradiated with various different doses.
The remaining film thickness (normalized) is calculated as the electron beam irradiation amount (coulombs/cd)
Figure 1 was obtained by plotting the electron beam sensitive characteristics.

From this, the minimum irradiation dose at which the residual film rate becomes zero was found: 2.8
X10-' coulombs/cd, and it was confirmed that the resist was an extremely sensitive positive resist.

For example, the electron beam sensitivity of polymethyl methacrylate, which is a typical positive resist, is 1 x 10 -' 1/d. A embossed structure could be formed with the amount.

Example 2 The copolymer of acetaldehyde and butyraldehyde obtained in Synthesis Example 2 was dissolved in toluene to prepare a 0.3% by weight resist solution. Subsequently, the above resist solution was applied onto a silicon wafer and prebaked at 80° C. for 20 minutes to form a 2.0 am thick polymer film. This was placed in a soft X-ray generator and irradiated with soft X-rays with a wavelength of 4.2 mm generated from a 10KW rotating water-cooled silver target in vacuum, and the residual film thickness (normalized) and soft X-ray irradiation amount were measured. (rrJ /
ad). The results are shown in Figure 2, and the minimum irradiation dose at which the film thickness becomes zero was determined to be 19m1/
-, and it was confirmed that it was an extremely sensitive positive resist. for example.

The soft X-ray sensitivity of polymethyl methacrylate, which is a typical positive resist, is approximately 2000 mT/'-, and the positive resist material of the present invention has a
It was confirmed that the material had high soft X-ray sensitivity of more than two orders of magnitude.

Examples 6 to 8 Synthesis examples 3 to 8. (The altehyde copolymer obtained in i3 was dissolved in xylene to create a resist solution of about 0.2% by weight.Next, the above resist solution was applied onto a silicon wafer and prebaked at 80°C for 20 minutes. Approximately 1.5am
A thick polymer film was formed.

The results are summarized in Table 2, and it was confirmed that all of the resists had high sensitivity to radiation and were highly sensitive positive resists.

Comparative Example Similar to the example, we attempted to evaluate acetaldehyde homopolymer or butyraldehyde homopolymer as resist materials, but we were unable to obtain any that were soluble in general-purpose organic solvents! Nothing of any use was obtained.

Table 2 The numbers within 0 represent the molar ratio in the copolymer.

Abbreviations of eight monomers: acetaldehyde BA inbutyraldehyde A nigerobanal PhPA: 5-phenylgropanal HA: heptanal IBA: inbutyraldehyde As is clear from the above explanation, according to the present invention, a small amount of radiation irradiation and without any development processing,
It is possible to manufacture embossed structures, and has a remarkable effect on the manufacture of semiconductors, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the electron beam sensitive characteristics of the radiation-sensitive polymer material of the present invention, and FIG. 2 is a diagram showing the soft X@ characteristics of the radiation-sensitive polymer material of the present invention. 2 1 Moon Stone 1

Claims (1)

[Claims] 1. By forming a thin film made of a radiation-degradable polymer material on a substrate and irradiating a desired portion of this polymer thin film with radiation, an embossed structure can be formed without any development process. How to manufacture the body. 2. A method for producing a relief structure according to claim 1, wherein the radiation-degradable polymer material is made of an aldehyde-based polymer.