JPH0329802B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a discharge graft polymer film that can be applied to a resist for forming fine patterns, and a method for manufacturing the same. In recent years, advances have been made in the technology of forming fine patterns using organic polymer resist compositions as partial mask materials for etching or impurity doping of various substrates and covering layers in the production of integrated circuits. . To form fine patterns using resist compositions, photophosphorography using visible light or ultraviolet light is usually used, but recently energy beams with extremely short wavelengths such as electron beams and X-rays have been used. Efforts are being made to improve the machining accuracy using the micro ring graphie used. Resist compositions for this purpose include polymethyl methacrylate (PMMA),
Organic polymers such as polyfluorinated alkyl methacrylates [e.g. polytetrafluoropropyl methacrylate (PFPM), polyhexafluorobutyl methacrylate (PFBM)] have been used [Kentaro Matsuyama, "Electron Beam and X-ray Resist Materials", Electronic Communication See Academic Journal Vol. 61, No. 8, p. 823 (1978), and Japanese Patent Application No. 14605/1982].Such organic polymers are produced by appropriately adding substances that have been made to have a high molecular weight through polymerization. It is dissolved in a suitable solvent and applied to a substrate using a spinner method or dip method to form a thin film.When using the spinner method or dip method, a large amount of solvent is required to turn the polymer into a solution. Defects such as pinholes are likely to occur on the surface.Furthermore, when using a substrate with steps, it has drawbacks such as the inability to apply uniformly on the step and poor adhesion to the substrate. In order to fabricate a resist thin film on a substrate, it has been desired to realize a so-called dry process that does not use a solvent. Dry etching, which processes the substrate using gas plasma such as CCl ₄ or CF ₄ , is becoming mainstream for the production of ultra-fine patterns. In addition, it is desired that the thin film be made of a material with strong gas plasma resistance during patterning after exposure and during substrate processing and etching processes. A method using polymerization has been developed (Japanese Patent Application No. 54-152069). Although the thin film growth rate is fast in this type of discharge polymerization, since the high energy of gas plasma is applied to the raw material gas, the produced thin film is Compared to ordinary polymers, the monomer structure was more likely to be destroyed, and the properties as a resist material (sensitivity, resolution) were often reduced.On the other hand, while the monomer structure was maintained, Photo-vapor phase polymerization is a possible method for thinning films in dry conditions, but it has problems such as low thin film formation rate, non-uniform film thickness due to condensation of monomers on the substrate, and contamination with photosensitizers. An object of the present invention is to solve the above-mentioned drawbacks and to provide a discharge graft polymer film and a method for producing the same, which can form a resist thin film on a substrate without using a solvent. To summarize the present invention, the first invention (polymer film) of the present invention has the following general formula (): (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group, a fluorinated alkyl group, or a glycidyl group). The present invention relates to a discharge graft polymer film characterized in that the present invention is polymerized by vapor phase graft polymerization to produce and laminate a corresponding polymer on the substrate. And the second invention (manufacturing method) of the present invention is
The following general formula () with the board installed: (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group, a fluorinated alkyl group, or a glycidyl group.) The present invention relates to a method for producing a discharge-grafted polymer film, characterized in that glow-discharge polymerization and gas-phase graft polymerization are repeated, thereby producing and laminating a corresponding polymer on the substrate. Hereinafter, the present invention will be specifically described based on the accompanying drawings. FIG. 1 is a schematic diagram of an example of a discharge graft polymerization apparatus used in the production method of the present invention. In FIG. 1, 1 is a reaction vessel, 2 and 3 are monomer gas inlets, 4 is an exhaust port, 5 is a substrate, 6 is a high frequency electrode, and 7 is a high frequency power source. Here, as the substrate 5, a material such as a silicon wafer, glass, or polyester can be used. Although a parallel electrode type is shown in FIG. 1 as the high frequency electrode 6, a coiled high frequency electrode can also be used in addition to the parallel electrode. Further, when glass or quartz is used as the reaction vessel 1, electrodes can be provided outside the vessel. FIG. 2 shows an example of the shape of a device using a coiled high-frequency electrode. That is, FIG. 2 is a schematic diagram of an example of an inductively coupled (coil type) discharge graft polymerization apparatus used in the production method of the present invention. In Figure 2, 2, 4
7 are the same as those in FIG. 1, and 8 is an insulating reaction vessel. To produce a discharge-grafted polymer film, first, the reaction vessel is evacuated, a monomer gas of 10 to 10 ^-3 Torr is introduced, a high-frequency voltage is applied to the electrode, and a discharge is generated in the gaseous monomer. let Due to this discharge, the monomers in the reaction vessel are polymerized, and a discharged polymer film consisting of the constituent atoms of the monomers is formed on the substrate. Next, the high frequency voltage application is stopped, and the flow state of the monomer gas continues. By doing so, gas phase graft polymerization is initiated with high initiation efficiency by the residual radicals on the surface of the discharged polymer film. Subsequently, discharge polymerization is performed by applying a voltage, and the same operation is repeated thereafter to form a discharge graft polymer film on the substrate. This process is shown in FIG. That is, FIG. 3 is a process diagram showing, in cross-sectional view, the products of each step in an example of producing a discharge graft polymer film by the production method of the present invention.
In FIG. 3, 5 is a substrate, 11 is a thin film produced by discharge polymerization, 12 is a thin film produced by graft polymerization during discharge termination, and 13 is a discharge graft polymer obtained by repeating the above process. It is a combined membrane. This process is performed at a gas pressure of 1×10 ^-3 to 1 torr during discharge,
Graft polymerization pressure 1×10 ^-2 ~10 torr and total glow discharge time/total gas phase graft polymerization time ratio 1 ~
It is preferable to repeat the process continuously at a rate of 1/1000. During discharge, it is difficult to maintain a stable discharge at a monomer gas pressure of less than 1×10 ⁻³ Torr, and it has been impossible to produce a thin film on the substrate. On the other hand, when monomer supply is maintained at high pressure, methyl methacrylate and fluorinated alkyl acrylate undergo a chain reaction in the gas phase during discharge polymerization at gas pressures exceeding 1 Torr, producing a snow-like bulky polymer powder. adheres to the inside of the reaction vessel and onto the substrate,
It has been impossible to create a thin film that completely covers the substrate. During graft polymerization, if the monomer pressure is less than 1 × 10 ^-2 Torr, the film thickness growth rate will be extremely low, and the thickness will be less than 0.5 μm.
It took more than 4 hours to obtain a film thickness of . Furthermore, the resulting film contained a large amount of oligomers, had low solvent resistance, and was dissolved in a developer containing methyl ethyl ketone/isopropyl alcohol = 1/9. If the monomer pressure exceeds 10 torr during graft polymerization,
The monomer condenses on the substrate due to the temperature difference in the reaction vessel,
A film containing oligomers was formed in the form of droplets, resulting in a highly uneven and non-uniform film. It also had poor solvent resistance and was dissolved in the above-mentioned developing solvent, making it impossible to use it as a resist. In the method of the present invention, the gas pressure during discharge and the pressure during graft polymerization may be the same or different. Next, to explain the ratio of total glow discharge time/total gas phase graft polymerization time, if the glow discharge time is long, as in the prior art described above, the monomer structure will be more destroyed, and the characteristics as a resist material will be affected. decrease. On the other hand, if the vapor phase graft polymerization time is extremely long, the film thickness growth rate decreases, and it is difficult to achieve a thickness that can be practically used as a resist film. Therefore, it has been found that the above-mentioned ratio of 1 to 1/1000 is suitable in terms of balance. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 A discharge graft polymer film of methyl methacrylate and fluorinated alkyl methacrylate was prepared on a silicon substrate under the polymerization conditions shown in Table 1 below. In Table 1, the monomers used have the formula H ₂ C=C
Only R in the methacrylate represented by (CH ₃ )COOR is shown.

[Table] The examples shown in Table 1 show some of the conditions under which a transparent and uniform film can be produced. Example 2 A high frequency voltage of 13.56 MHz was applied to a reaction vessel into which 6.0×10 ^-2 Torr of methyl methacrylate was introduced, the discharge was performed for 0.1 minute at a discharge power of 10 W and a gas flow rate of 20 c.c./min, and the discharge was stopped for 0.9 minutes. Then, the monomer was continued to flow at a pressure of 1 Torr and gas phase graft polymerization was carried out for 60 minutes to obtain a discharge graft polymer film having a thickness of 0.9 μm. Applied voltage 20KV on this film, current amount 1×
A line pattern was drawn with a 10 ^-9 A electron beam. This was developed with methyl ethyl ketone/isopropyl alcohol=1/9 to obtain a drawn positive line pattern. The amount of electron beam irradiation required to produce a pattern with a residual film thickness of 90% in the unexposed area was 1×10 ⁻⁵ c/cm ² .
This is compared to a discharge polymer film using methyl methacrylate as the same monomer (1979 Proceedings of the Japan Society of Applied Physics, 29p-s-13, "Electron Beam Drawing and Plasma Etching on PMMA Films" Gono, Ieda et al.). It showed about 5 times higher sensitivity. Furthermore, when a similar film is dry-developed in a cylindrical gas plasma apparatus using CCl ₄ gas, the electron beam irradiation amount required to create a pattern with a residual film thickness of 80% in the unexposed area is still 1 × 10 ^-5 c / ^cm2 . Into a reaction vessel into which 6.0×10 ^-2 Torr of methyl methacrylate was introduced, under the above conditions, a discharge time of 2 minutes was carried out, and gas phase graft polymerization was carried out at a gas pressure of 1 Torr for 0.5 minutes, alternating with each other. This process was repeated for 25 minutes to obtain a discharge grafted polymer membrane with a thickness of 1.2 μm. An electron beam of 1×10 ^-5 c/cm ² and 5×10 ^-5 c/cm ² was applied on this film under the above conditions.
The pattern was drawn with an electron beam irradiation dose of 1×10 ⁻⁴ c/cm ² . When developed with a developer containing methyl ethyl ketone/isopropyl alcohol = 1/9, no positive patterns were observed in the films of any irradiation dose. If you use methyl ethyl ketone (100%) as the developing solvent, which has even stronger dissolving power, and perform the development, ^the
A pattern could be formed in the sample with an electron beam irradiation dose of cm ² . On the other hand, in the 5×10 ^-5 c/cm ² and 1×10 ^-5 c/cm ² samples, lines in the exposed area could be observed, but
The solubility of the exposed area was poor, resulting in an incomplete pattern. This indicates that the rate of discharge polymerization in the discharge-grafted polymer film is too high, resulting in destruction of the basic monomer structure and resulting in a crosslinked structure, resulting in a decrease in electron beam sensitivity. Example 3 Tetrafluoropropyl methacrylate (Table 1
4) was subjected to discharge graft polymerization under the conditions of 5 in Table 1 to obtain a discharge graft polymer film of 1.0 μm in polymerization time of 25 minutes. A 3 μm thick pattern mask (formed on a 3 μm thick polyimide film) was brought into close contact with this, and the Mo target was irradiated with soft X-rays. Developing was carried out under the same conditions as in Example 1 to obtain a positive transfer pattern of the mask pattern.
The amount of X-rays required for pattern formation was approximately 200 mJ/cm ² . Example 4 A pattern was prepared using the discharge grafted polymer film of 1 in Table 1 on an Al vapor-deposited substrate, and using this as a mask, dry etching of Al was performed with CCl ₄ gas using a parallel electrode type plasma etching apparatus. I did the processing. Al etching speed is 1500Å/
Minutes, the discharge-grafted polymer film underwent etching of approximately 800 Å/min. Commercially available under the same conditions
The PMMA resist film (Elversite® 2041) was etched at 1200 Å/min.
Therefore, it was found that the dry etching resistance of the discharge graft polymer film was improved by about 50%. Example 5 On a silicon wafer, 1×10 ^-1 Torr, flow rate 20
Hexamethyldisilazane [(CH ₃ ) ₃ −Si−NH−Si−(CH ₃ ) ₃ ] at 0.5 cc/min and discharge power of 15 W.
The wafer surface is coated by discharge polymerization for a minute. Subsequently, hexafluorobutyl methacrylate (6 in Table 1) was subjected to discharge graft polymerization for 40 minutes under the conditions of 6 in Table 1 to obtain a 0.92 μm discharge graft polymer film. When a solution obtained by polymerizing monomer 6 in Table 1 by conventional polymerization is applied by spin coating, the problem is that the adhesion to the Si surface is poor. For this,
Normally, the wafer surface is treated with a solution of a surface treatment agent such as hexamethyldisilazane, but in the present invention, this surface treatment step can also be made dry. When this discharge-grafted polymer film was subjected to electron beam lithography under the conditions of Example 2, it was possible to produce a good pattern with a sensitivity of 7×10 ^-6 c/cm ² and no pattern peeling from the substrate. . Example 6 Glycidyl methacrylate was deposited on a silicon wafer at a gas partial pressure of 8×10 ^-2 Torr and a flow rate of 16 c.c./min. Ethyl acrylate was deposited on a silicon wafer at a gas partial pressure of 2×10 ^-2 Torr and a flow rate of 4.
A discharge graft polymer film of 1.0 μm was produced by repeating discharge for 0.1 minutes and stopping the discharge for 0.9 minutes while flowing at a rate of cc/min and discharging for 0.1 minutes and stopping the discharge for 0.9 minutes to produce a discharge graft polymer film of 1.0 μm. When this discharge graft polymer film was subjected to electron beam drawing and solvent development, a negative drawing pattern was obtained. The amount of electron beam irradiation necessary to obtain the pattern was 2×10 ⁻⁶ c/cm ² . Example 7 Methyl methacrylate was poured onto a silicon wafer at a gas pressure of 6×10 ^-2 Torr and a flow rate of 20 c.c./min, and discharged for 0.1 minute at a discharge power of 10 W. Discharge was stopped for 1.5 hours, and the gas pressure was reduced to 1. Gas-phase graft polymerization was carried out at Tor. When this process was repeated twice, it took approximately 3 hours to produce a 0.12 μm discharge graft polymer film on the wafer. Apply electron beam drawing to this film at a voltage of 20KV,
Current amount 1×10 ^-9 A, electron beam irradiation amount 3×10 ^-5 c/cm ²
After developing under the following conditions, development was carried out using only isopropyl alcohol. Through this development, a positive pattern could be produced on the wafer. The gas phase graft polymerization time was set to 2 hours under the above conditions, and this was repeated twice. A 0.09 μm discharge graft polymer film was produced on the wafer in about 4 hours. After performing similar electron beam drawing on this film, it was developed with isopropyl alcohol.
No pattern could be formed, and the film was partially dissolved from the substrate, leaving only a few island-like films. As shown here, when the vapor phase graft polymerization time is extremely prolonged during discharge graft polymerization, the film thickness growth rate decreases, and it is difficult to grow the film to a thickness that can be used as a resist film. As described above, the discharge graft polymer film according to the present invention can be easily formed into a thin film on a substrate in a gas phase without using a solvent or a sensitizer. Furthermore, compared to discharge polymer films obtained by continuous discharge polymerization at high discharge power, the basic monomer structure is less destroyed, and the resulting thin film has properties close to those of ordinary polymers. Furthermore, a part of the prepared discharge graft polymer film can be used as a positive or negative resist material as shown in the above example, and its sensitivity to energy rays is very high, and it can be used in dry conditions. If coating and dry etching are used together,
It has the advantage of completely dry microfabrication.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a discharge graft polymerization apparatus used in the production method of the present invention. FIG. 2 is a schematic diagram of an example of an inductively coupled (coil type) discharge graft polymerization apparatus. FIG. 3 is a process diagram showing, in cross-sectional view, the products of each step in an example of producing a discharge graft polymer membrane according to the production method of the present invention. 1: Reaction container, 2 and 3: Monomer gas inlet,
4: Exhaust port, 5: Substrate, 6: High frequency electrode, 7: High frequency power supply, 8: Insulator reaction vessel, 13: Discharge graft polymer film obtained by repeating discharge polymerization and gas phase graft polymerization.

Claims (1)

[Claims] 1. On the substrate, the following general formula (): (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group, a fluorinated alkyl group, or a glycidyl group). A discharge graft polymer film characterized in that the corresponding polymer is produced and laminated on the substrate by polymerizing with and by vapor phase graft polymerization. 2 The following general formula () with the board installed: (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group, a fluorinated alkyl group, or a glycidyl group.) 1. A method for producing a discharge-grafted polymer film, the method comprising: starting the process, and then repeating glow-discharge polymerization and gas-phase graft polymerization, thereby producing and laminating a corresponding polymer on the substrate. 3 Polymerization of the monomer is carried out at a gas pressure of 1×10 ^-3 during discharge.
1 torr, pressure during graft polymerization of 1×10 ^-2 to 10 torr, and a total glow discharge time/total gas phase graft polymerization time ratio of 1 to 1/1000. A method for producing a discharge-grafted polymer membrane.