JPH0376454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel negative radiation-sensitive resist material used in microfabrication techniques during the manufacturing process of solid-state devices such as semiconductor elements and integrated circuits, and a method for manufacturing the same.

Recently, demands for higher density, higher speed, and smaller integrated circuits have required the formation of fine patterns, and there is an urgent need to develop lithography technology to replace light. Therefore, microfabrication techniques using radiation having shorter wavelengths than light, such as X-rays and electron beams, have been developed. There are a wide range of performance requirements for resist materials, including sensitivity, resolution, etching resistance, especially dry etching resistance, development tolerance, post-polymerization, and stability, but conventionally developed resist materials meet all of these requirements. The performance was not satisfactory. For example, positive resists such as polymethyl methacrylate have sufficiently good resolution, but have poor sensitivity and dry etching resistance, making them difficult to use practically, and negative resists such as polyglycidyl methacrylate. has high sensitivity and good throughput, but its resolution and dry etching resistance are poor, and improvements are strongly desired. In particular, negative resists generally have poor resolution, and there has been a desire to develop materials that exhibit high resolution.

Some of the present inventors previously reported that polystyrene with a narrow molecular weight distribution exhibits high resolution;
It was reported that it was good as a resist material (J. Electrochem. Soc., 129(3), 663 (1982)).

As a result of further intensive research, the inventors found that
Radiation-sensitive resist materials containing polymers containing specific repeating units as active ingredients exhibit higher sensitivity, and when such materials are used, extremely sharp micropatterns can be formed, improving sensitivity and dry etching resistance. It has been discovered that other performance requirements such as the above can also be satisfied, and the present invention has been achieved.

That is, the gist of the present invention is that the formula () A radiation-sensitive resist material characterized in that the active ingredient is a polymer containing a repeating unit represented by Formula () obtained by performing lower polymerization A method for producing a radiation-sensitive resist material, characterized by using a polymer represented by:

To explain the present invention below, the radiation-sensitive resist material used in the present invention contains a polymer containing a repeating unit represented by the above formula () as an active ingredient. Examples of such polymers include polymers consisting only of repeating units represented by the above formula (), ie, poly-4-vinyl phenyl crotyl ether, and copolymers with other monomers. Copolymerizable monomers include diene monomers and styrene monomers, ie, butadiene; isoprene; 1-phenylbutadiene;
Examples include 2,3-dimethylbutadiene; styrene; P-chlorostyrene; P-bromostyrene.

The polymer used in the present invention can be produced by anionic polymerization of the corresponding monomer according to a known method. In particular, when anionic polymerization of 4-vinylphenyl crotyl ether is performed using cumyl cesium as a polymerization initiator in a solvent such as tetrahydrofuran at -60°C or lower, it produces a polymer with a high yield and an extremely sharp molecular weight distribution. can be obtained.

In the present invention, the above-mentioned polymers,
Furthermore, if necessary, various known additives such as sensitizers, stabilizers, etc. are dissolved in a solvent such as ethyl cellosolve acetate to prepare a coating solution, and according to a conventional method,
A radiation-sensitive resist material is usually prepared by coating a substrate such as a silicon wafer or a glass substrate to a film thickness of 2,000 to 20,000 Å.

This radiation-sensitive resist material is irradiated with short-wavelength radiation such as X-rays and electron beams depending on the image, and then developed with a developer such as a methyl ethyl ketone-ethanol (7:1) mixed solution. It is possible to form a strong resist.

Next, the present invention and its effects will be explained by examples, but the present invention is not limited by these in any way.

Example 1 1 Synthesis of monomer (4-vinylphenyl crotyl ether) Synthesis was carried out in the following three steps.

(1) Etherification (synthesis of 4-acetylphenyl crotyl ether) Pour 250 ml of ethanol into a three-necked flask,
Next, 140.4g of P-acetylphenol
(1.032 mol); 142.6 g (1.032 mol) of potassium carbonate; and 16.5 g (0.1 mol) of potassium iodide were added and dissolved with stirring. 93.4 g (1.032 mol) of crotyl chloride was added from the dropping funnel, and further 250 ml of ethanol was added. After refluxing for 49 hours,
The ethanol in the liquid was distilled off, ether and 5% sodium hydroxide aqueous solution were added to the residue, and the mixture was shaken in a separatory funnel. After separation, the ether layer was washed with water, dried over potassium carbonate, and the ether was distilled off. The residue was removed and distilled under reduced pressure. 4-
Acetyl phenyl crotyl ether was obtained with a yield of 90%.

(2) Reduction (synthesis of 4-(α-hydroxyethyl)-phenyl crotyl ether) 400ml of methanol and 9.0ml of sodium hydroxide
g, sodium borohydride 18.4 g (0.487
mol) was dissolved while cooling, and 4-acetylphenyl crotyl ether was added dropwise, followed by refluxing for 4 hours. After distilling off methanol, ether was added, washed with water, and dried over sodium sulfate. After distilling off the ether, vacuum distillation is performed.
(α-Hydroxyethyl)phenyl crotyl ether was obtained in a yield of 81%.

(3) Dehydration (synthesis of 4-vinylphenyl crotyl ether) Grind 0.35 g of potassium hydrogen sulfate and 0.1 g of t-butylcatechol in a mortar, add 75 g of 4-(α-hydroxyethyl)-phenyl crotyl ether, Heat to 190℃,
The pressure inside the system was reduced to 2 mmHg. After almost no water was distilled off, the reaction was stopped, ether was added, the mixture was washed with a 5% aqueous sodium hydroxide solution and water, dried over sodium sulfate, and then distilled. 4-vinylphenyl crotyl ether was obtained with a yield of 50%. (bp.2mmHg99~101
℃) 2 Polymerization (Anionic polymerization of poly-4-vinyl phenyl crotyl ether) (1) Purification of monomer This was carried out in the following three steps.

() The monomer and calcium hydride were stirred in a vacuum line (10 ^-4 mmHg) for 3 hours and distilled. (Dehydration, degassing) () Benzophenone-sodium and monomer were distilled while stirring in a vacuum line (10 ^-6 mmHg). (Removal of impurities) () In a similar vacuum line, triphenylmethyl lithium, lithium bromide, and monomer were distilled with stirring.

The above distillation was carried out under reduced pressure while keeping the temperature below 100°C.

(2) Purification of solvent Tetrahydrofuran (THF), which had been previously dried with calcium hydride and sodium wire, was stirred for 5 hours in the presence of anthracene and metallic sodium pieces in a vacuum line (10 ^-4 mmHg), and then distilled. Furthermore, a THF solution of α-methylstyrene tetramer disodium salt was added and distilled with stirring.

(3) Polymerization Polymerization was carried out using the polymerization apparatus shown in Figure 1.

First, the pressure inside the system was reduced to 10 ^-6 mmHg, and then the system was disconnected from the vacuum line at position 8. The inside of the system was washed with a tetrahydrofuran solution of α-methylstyrene tetramer disodium salt in reagent tank 1, collected in recovery tank 2, and separated at position 9.

Next, the polymerization initiator cumyl cesium 1.1 in reagent tank 3
x10 ^-4 mol was put into reaction tank 6, and then 60 ml of tetrahydrofuran, the solvent in reagent tank 4, was added while stirring. After cooling to -78℃, monomer (4-
Add 5g of vinyl phenyl crotyl ether), 3
After polymerization for a period of time, the apparatus was opened, methanol was added to stop the reaction, and the polymer precipitate was separated.
After drying, it was dissolved in benzene and freeze-dried. A yield of 4.6 g (93% yield) of polymer was obtained.

The molecular weight of this polymer was measured using GPC (manufactured by Toyo Soda Co., Ltd.).
HLC-827 type). The measurement results are shown in Figure 2. As is clear from FIG. 2, n=11.1×10 ⁴ ,
A polymer with a sufficiently large molecular weight (Mw/n=1.08) and a sharp molecular weight distribution was obtained.

Example 2 A 5% ethyl cellosolve acetate solution of poly-4-vinyl phenyl crotyl ether obtained in Example 1 was prepared, overpurified using a membrane filter with a pore size of 0.2 μm, and spin-coated onto a silicon wafer. A film thickness of 3500 Å was obtained. This sample was irradiated with an electron beam (EBX-5A 20KV) and the sensitivity curve was measured, and the results shown in FIG. 3 were obtained.

Development was carried out by immersion in a 7:1 mixture of methyl ethyl ketone and ethanol for 2 minutes. If the irradiation amount at 80% residual film thickness is used as an indicator of sensitivity, it will be 2.0×10 ^-6 C/cm ²
is obtained, and this value is changed to the polystyrene value 6.5×
The sensitivity was about 33 times higher than that of 10 ^-5 C/cm ² . Also, γ=2.3 also gave good results. Also, irradiation amount
When a fine pattern with a spacing of 1 μm was formed at 2.7×10 ⁻⁶ C/cm ² , an extremely sharp image was obtained.
A scanning electron microscope (SEM) photograph is shown in Figure 4.

Next, dry etching (manufactured by Plasma Thermo)
When subjected to HFS-3000D gas (CF ₄ /O ₂ =95/5), it showed sufficient resistance.

As described above, this resist was found to be extremely excellent as a radiation-sensitive resist.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of the polymerization apparatus used in Example 1. FIG. 2 shows the results of molecular weight measurement of the polymer obtained in Example 1. In the figure, curves 11, 12 and 13 show the results measured for polymers polymerized at monomer concentrations of 8%, 14% and 17%, respectively. FIG. 3 shows the sensitivity curve measured in Example 2. The horizontal axis shows the dose, and the vertical axis shows the film thickness after development (ratio to the initial film thickness). FIG. 4 shows Example 2
A scanning electron micrograph of the resist pattern obtained in . 1, 3, 4, 5... Reagent tank, 6... Reaction tank, 7
...Teflon stirrer.

Claims (1)

[Claims] 1 Formula () 1. A radiation-sensitive resist material characterized by containing a polymer containing a repeating unit represented by as an active ingredient. 2 Formula obtained by polymerizing a reaction raw material containing 4-vinylphenyl crotyl ether in the presence of cumyl cesium as a polymerization initiator () 1. A method for producing a radiation-sensitive resist material, comprising using a polymer containing a repeating unit represented by: