JPH0380301B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to semiconductor devices, magnetic bubble memory devices,
The present invention relates to a radiation-sensitive organic polymer material that is highly sensitive to radiation such as electron beams, X-rays, and ion beams and is suitable for forming fine patterns necessary for manufacturing integrated circuits. [Background of the Invention] Conventionally, methods using photoresists sensitive to ultraviolet or visible light have been widely put into practical use as pattern forming methods for manufacturing electronic components such as semiconductor devices, magnetic bubble memory devices, and integrated circuits. ing. In recent years, for the purpose of increasing the density and integration of semiconductor devices, there has been a demand for a method for forming patterns with a width of 1 μm or less. However, with the above-mentioned method using light, it is extremely difficult to accurately form patterns with a width of 1 μm or less due to the inherent properties of the light, such as diffraction, scattering, and interference, and at the same time, the yield may decrease. Significantly, methods using ultraviolet light or visible light are unsuitable for forming patterns with a width of 1 μm or less. In order to deal with this, lithography techniques using high-energy radiation such as electron beams, Various sensitive materials have been studied. Among these, positive-type radiation-sensitive organic polymer materials, such as poly( Methyl methacrylate), poly(1-butenesulfone), etc. induce a crosslinking reaction by irradiation with radiation,
The irradiated portion becomes insoluble in the developer, and it can generate patterns with higher resolution than negative radiation-sensitive organic polymer materials that form patterns, making it extremely advantageous as a resist material for microfabrication. However, the sensitivity of positive-tone radiation-sensitive organic polymer materials, including the above-mentioned materials, is 1/10 to 1/1000 lower than that of negative-tone materials, and as a result, the time required for pattern formation is longer. It was impractical in terms of productivity. Furthermore, when considering the manufacture of semiconductor devices and the like, several resist steps are used. Each resist process requires resist coating, drying, irradiation with light or radiation, and development, and development using a typical wet process takes several tens of minutes. After developing the resist, the time required to move the wafer to the next processing step is even more time-consuming, and there has been a strong desire in the semiconductor industry for rapid development processing and processing methods that use little wet solvents. [Object of the Invention] The object of the present invention is to eliminate the drawbacks of the prior art as described above, and to provide a positive radiation-sensitive organic material having high sensitivity to high-energy radiation such as electron beams, X-rays, and ion beams. The object of the present invention is to provide a polymeric material with positive radiation sensitivity, which is characterized by the fact that when irradiated with radiation, the irradiated part disintegrates and scatters in a chain, so that a pattern can be formed without a special development process. Our objective is to provide organic polymer materials. [Summary of the Invention] In order to achieve the above object, the present inventor has studied various organic polymer materials that are thought to have radiation sensitivity, and has found 4, 4,
We have now discovered an aldehyde-based polymer in which a mixture of 4-triphenylbutanal (hereinafter abbreviated as TPhBA) and one or more aliphatic aldehydes is copolymerized with each other. In other words, the aldehyde-based polymerization modification having a polyether type structure as described above is extremely difficult because the polymer chains are chain-disintegrated by irradiation with high-energy radiation such as electron beams, X-rays, and ion beams. It can be used as a highly sensitive positive resist material, and since the irradiated area is scattered at the same time as the radiation is irradiated, patterns can be formed without using a special development process, and the manufacturing process can therefore be extremely shortened. It is characterized by being a self-imaging positive resist material. Next, materials used in the present invention will be explained. Generally, 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 to obtain a polymer that can be used as a resist material by improving the solubility of aldehyde polymers. It has been found that aldehyde copolymers obtained by polymerization can be used as radiation-sensitive organic polymer materials. The aliphatic aldehyde monomer used in the copolymerization with TPhBA in the present invention has the general formula R-CHO
, R is one or more aldehyde monomers selected from aliphatic aldehydes such as an alkyl group, a halogenated alkyl group, an aralkyl group, or a halogenated aralkyl group, and the above alkyl group is Preferably, it has 1 to 8 carbon atoms. When the proportion of the monomer mixture is regulated by the polymer composition, it is selected from a composition 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 95 mol%. The method for producing the polymer of the present invention is not particularly limited, but includes, for example, an anionic polymerization method using ethylmagnesium bromide-(-)-Sparteine as a catalyst. Although there is no limit to the amount of catalyst added, it is appropriate to add the catalyst in an amount of 0.1 to 5 mol % based on the aldehyde monomer mixture. In carrying out anionic polymerization, it is not necessary to use a polymerization medium, but if necessary, it is preferable to use a hydrocarbon solvent such as toluene. The polymerization can be carried out at a temperature of 0°C to -120°C, but it is usually preferably carried out at a temperature of -50°C to -100°C. When the radiation-sensitive organic polymer material of the present invention is used to form patterns for semiconductor devices, etc., it is dissolved in a general-purpose organic solvent such as chloroform or toluene, and is usually spun. The element substrate is coated by a coating method or a dip coating method. After coating, pre-baking at appropriate temperature conditions, and then irradiating the desired pattern with radiation, the irradiated area collapses and scatters in a chain, creating a positive resist pattern without the need for a developing process. be able to. Note that, if necessary, wet development may be performed using a chloroform-isopropyl alcohol organic solvent. Further, the aldehyde polymer of the present invention exhibits high sensitivity to radiation, but also sensitivity to light, and can be used as a photosensitive material. [Examples of the Invention] The present invention will be specifically explained below with reference to synthesis examples and examples. Synthesis Example 1 4,4,4-triphenylbutanal was synthesized as follows. In a 500 ml three-necked flask equipped with a reflux condenser and a dropping funnel, 3.4 g of NaBH ₄ was added under nitrogen flow.
74 g of 4,4,4-triphenyl-1-butene and 190 ml of tetrahydrofuran were added. 25 for this
While stirring at °C, 21 g of BF ₃ .O(C ₂ H ₅ ) ₂ was added dropwise over 2 hours. After the dropwise addition, stirring was continued for an additional 6 hours. Next, add 20 ml of water to the reaction mixture,
33 _ml of NaOH aqueous solution and 33 ml of 30% _H2O2 aqueous solution were added in this order. The aqueous layer was saturated with NaCl, the organic layer was separated, and this layer was washed with saturated brine. After drying with MgSO ₄ , the solvent was distilled off to obtain a crude product. This was recrystallized from hexane to obtain 32 g (40% yield) of 4,4,4-triphenylbutanol. Melting point: 113
~116℃. 128 g of anhydrous pyridine and 2.1 g of anhydrous methylene chloride were added to the three-necked flask in Step 3, and 82 g of chromium oxide (2) was dissolved therein at room temperature. To this, 4,4,4-triphenylbutanal obtained in the above reaction
Add a solution of 41g dissolved in 145ml of methylene chloride,
Stir for 20 minutes. Next, the organic layer was separated and mixed with 500 ml of 5% NaOH aqueous solution, 500 ml of 5% hydrochloric acid, and 5%
It was washed successively with 500 ml of NaHCO ₃ aqueous solution and saturated saline, and dried with MgSO ₄ . The crude product obtained by distilling off the solvent was repeatedly recrystallized from hexane.
4,4,4-triphenylbutanal 14g (yield
34%). Melting point: 106-107℃. Elemental analysis (C ₂₂ H ₂₀ O): Calculated values C 87.96%, H 6.71% Actual values C 87.94%, H 6.75% Infrared absorption spectrum (Nujiol method): 1722 cm ^-1 C=O 2720 cm ^-1

[Formula] ¹ H NMR spectrum (CDCl ₃ ): δ = 2.33 (2H, CH ₂ −CO−) 2.96 (2H,

[Formula]) 7.21 (15H, phenyl) 9.55 (1H, CHO) Synthesis example 2 C ₂ H ₅ MgBr-(-)-Sparteine complex was synthesized as follows. Add 1.5 ml of dry toluene, 0.53 ml of an ether solution of C ₂ H ₅ MgBr (1.5 mol/), and 0.95 ml of a toluene solution of (-)-Sparteine (1.02 mol/) to a 20 ml reaction tube with a three-way tank under nitrogen flow. Add warm;
_{A C2H5MgBr} -(-)-Sparteine complex was prepared. Synthesis Example 3 Polymerization was carried out using a polymerization tube with a three-way socket.
That is, 1.3 mmol of 4,4,4-triphenylbutanal (TPhBA) and n-butanal (BA) were placed in a cylindrical polymerization tube with a volume of approximately 100 ml under a nitrogen stream.
Add 11.7 mmol and 3 ml of toluene. The above polymerization tube containing the monomer solution was cooled to -78°C in a dry ice-acetone bath, and while stirring the container vigorously, 0.26 mmol of C ₂ H ₅ MgBr-(-)-Sparteine was added.
The complex was gradually added dropwise. -78℃ after adding catalyst
Polymerization was carried out for 24 hours. After polymerization, the polymerization mixture was treated with methanol containing HCl equimolar to the catalyst;
The resulting polymer was soaked in methanol for one day, separated, washed several times with methanol, and dried under vacuum to obtain an aldehyde copolymer with a yield of 51%. When the TPhBA content in the copolymer was determined by elemental analysis,
It was 9 mol%. Synthesis Examples 4 to 7 In the same manner as in Synthesis Example 3, TPhBA and various aldehyde monomers were copolymerized. The results are summarized in Table 1.

[Table] Example 1 The copolymer of 4,4,4-triphenylbutanal (TPhBA) and n-butanal (BA) obtained in Preparation Example 3 was dissolved in chloroform, and 1% by weight of the copolymer was dissolved in chloroform.
A resist solution was prepared. Next, the above resist solution was applied to a silicon wafer and prebaked at 80°C for 20 minutes to form a 3.5 μm film.
A thick polymer film was formed. This was placed in an electron beam irradiation device and irradiated with an electron beam in vacuum at an acceleration voltage of 20 KV, with different doses depending on the location. As a result, the film of the irradiated area was removed without any development treatment, and the remaining polymer film was measured using a thin-film step meter in areas irradiated with various different doses, and the remaining film thickness (normalized ) was plotted against the electron beam irradiation dose (clones/cm ² ) to obtain Figure 1, which shows the electron beam sensitivity characteristics. From this, the minimum irradiation dose at which the residual film rate would be zero was determined to be 1.7×10 ^-6 clones/cm ² , confirming that it is an extremely sensitive positive resist. For example, the electron beam sensitivity of polymethyl methacrylate, which is a typical positive resist, is 1 × 10 ^-4 clones/cm ² , and the polyurethane resist material of the present invention has a sensitivity of about two orders of magnitude compared to polymethyl methacrylate. It was confirmed that it exhibits high sensitivity. Example 2 The copolymer of TPhBA and BA obtained in Synthesis Example 3 was dissolved in chloroform to prepare a 1% by weight resist solution. Next, the above resist solution was applied onto a silicon wafer, prebaked at 80°C for 20 minutes, and a 2.3μ
A polymer film with a thickness of m was formed. This is placed inside a soft X-ray generator and placed under vacuum.
Soft X-rays with a wavelength of 5.4 Å generated from a 10 Kw rotary water-cooled molybdenum targate were irradiated, and the relationship between the residual film thickness (normalized) and the soft X-ray irradiation amount (mJ/cm ² ) was determined. The film on the irradiated area peeled off without any development, but even with a high irradiation dose, the film was removed by about 30%.
A residual film was observed. Sensitivity is defined as the minimum irradiation dose at which the film thickness remains constant after irradiation, and was found to be 380mJ/cm ²
It was confirmed that polymethyl methacrylate (soft X-ray sensitivity: 2000 mJ/cm ² ), which is a typical positive resist, has a soft X-ray sensitivity that is approximately one order of magnitude higher than that of a typical positive resist. Examples 3 to 6 Synthesis Examples The aldehyde copolymer obtained in steps 4 to 7 was dissolved in chloroform to prepare a resist solution of approximately 0.5% by weight.The above resist solution was then applied onto a silicon wafer and prebaked at 80°C for 20 minutes to form a resist solution of approximately 0.5% by weight. 2μ
A polymer film with a thickness of m was formed. Next, an electron beam with an accelerating voltage of 20KV is irradiated,
The electron beam sensitivity was determined. 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.

[Table] [Effects of the Invention] As is clear from the above explanation, according to the present invention, it is highly sensitive to radiation such as electron beams and X-rays,
Embossed structures can be manufactured without any development treatment after irradiation, and this method has a remarkable effect on the manufacture of semiconductor devices and the like.

[Brief explanation of drawings]

The figure shows the electron beam-sensitive characteristics of the radiation-sensitive polymer material of the present invention.

Claims (1)

[Claims] 1 4,4,4-triphenylbutanal and an aliphatic aldehyde monomer represented by the general formula R-CHO (wherein R represents an alkyl group, a halogenated alkyl group, an aralkyl group, or a halogenated aralkyl group) A radiation-sensitive organic polymer material characterized in that it is made of a material copolymerized with one or more aldehyde monomers selected from the following.