Preparation method of patterned substrate

Abstract

A method for preparing a patterned substrate includes selectively etching any one segment block of a self-assembled block copolymer from a laminate having a substrate; wherein a block copolymer membrane is formed on the substrate and the substrate contains the self-assembled block copolymer. According to the method, the self-assembled pattern of the block copolymer can be efficiently and accurately transferred on the substrate to prepare a patterened substate.

Claims

1. A method for preparing a patterned substrate comprising: selectively etching any one segment block of a self-assembled block copolymer from a laminate having a substrate; wherein a block copolymer membrane is formed on the substrate and the substrate contains the self-assembled block copolymer, wherein the selectively etching is performed using a reaction gas containing fluorocarbon and oxygen, and the selectively etching is performed while maintaining a ratio (A/B) of a flow rate (A) of the fluorocarbon to a flow rate (B) of the oxygen in a range of 0.5 to 7.5, wherein the self-assembled block copolymer comprises a polymer segment A block including a chain having 8 or more chain-forming atoms and a polymer segment B block having a structure different from that of the polymer segment A block, wherein the polymer segment A block comprises a ring structure and the chain is substituted on the ring structure, and wherein the ring structure of the polymer segment A block comprises no halogen atom and the polymer segment B block has a ring structure including a halogen atom.

2. The method according to claim 1, wherein the selectively etching maintains a flow rate of fluorocarbon of more than 0 sccm and 50 sccm or less.

3. The method according to claim 1, wherein the selectively etching maintains a flow rate of oxygen of more than 0 sccm and 35 sccm or less.

4. The method according to claim 1, wherein the selectively etching further supplies an inert gas at a flow rate of 200 sccm or less.

5. The method according to claim 4, wherein the etching maintains the ratio (A/C) of the flow rate (A) of the fluorocarbon to the flow rate (C) of the inert gas in a range of 0.1 to 1.

6. The method according to claim 1, wherein the fluorocarbon has two or more fluorine atoms and a molar ratio (F/C) of the fluorine atom (F) to the carbon atom (C) is 2 or more.

7. The method according to claim 1, wherein the reaction gas in the selectively etching consists of fluorocarbon and oxygen, or consists of fluorocarbon, oxygen and an inert gas.

8. The method according to claim 1, wherein a range of the applied electric power in the etching step is maintained in the range of 150W to 400W.

9. The method according to claim 1, wherein the selectively etching is performed in a chamber in which two opposite cathode and anode are present, the substrate on which the block copolymer membrane is formed is positioned on the cathode between the cathode and the anode, and an RF power source is applied to the cathode.

10. The method according to claim 1, wherein the block copolymer comprises a polymer segment A block and a polymer segment B block having a structure different from that of the polymer segment A block, and the polymer segment A block and the polymer segment B block each comprise a ring structure.

11. The method according to claim 10, wherein the ring structure of the polymer segment A block comprises no halogen atom, and the ring structure of the polymer segment B block comprises a halogen atom.

12. The method according to claim 10, wherein a chain having 8 or more chain-forming atoms is substituted on the ring structure of the polymer segment A block.

13. The method according to claim 1, further comprising etching the substrate using the block copolymer membrane, from which the any one segment block has been removed, as a mask.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an SEM image of the self-assembled structure of the block copolymer of Example 1.

(2) FIG. 2 is an SEM image of the block copolymer of Example 1 after etching.

(3) FIG. 3 is an SEM image of the block copolymer of Example 2 after etching.

(4) FIG. 4 is an SEM image of the self-assembled structure of the block copolymer of Example 3.

(5) FIG. 5 is an SEM image of the block copolymer of Example 3 after etching.

(6) FIG. 6 is an SEM image of the result of performing a pattern transfer on the etched block copolymer membrane of Example 2.

(7) FIG. 7 is an SEM image of the block copolymer of Comparative Example 1 after etching.

(8) FIG. 8 is an SEM image of the block copolymer of Comparative Example 2 after etching.

(9) FIG. 9 is an SEM image of the block copolymer of Comparative Example 3 after etching.

(10) FIG. 10 is an SEM image of the block copolymer of Comparative Example 4 after etching.

(11) FIG. 11 is an SEM image of the block copolymer of Comparative Example 5 after etching.

(12) FIG. 12 is a schematic diagram of a reactive ion etching apparatus.

MODE FOR THE INVENTION

(13) Hereinafter, the present application will be described more in detail by way of examples according to the present application and comparative examples, but the scope of the present application is not limited by the following examples.

(14) 1.GPC (gel permeation chromatography)

(15) The number average molecular weight (Mn) and the molecular weight distribution were measured using GPC (Gel Permeation Chromatography). Analytes are introduced into a 5 mL vial and diluted in THF (tetrahydrofuran) so as to be a concentration of about 1 mg/mL. Then, the calibration standard sample and the sample to be analyzed were filtered through a PTFE syringe filter (pore size: 0.45 μm) and then measured. As an analytical program, ChemStation from Agilent Technologies was used, and the elution time of the sample was compared with the calibration curve to obtain the weight average molecular weight (Mw) and the number average molecular weight (Mn), respectively, and to calculate the molecular weight distribution (PDI) from the ratio (Mw/Mn). The measurement conditions of GPC are as follows.

(16) <GPC measurement conditions>

(17) Device: 1200 series from Agilent Technologies

(18) Column: using two PLgel mixed B from Polymer laboratories

(19) Solvent: THF

(20) Column temperature: 35° C.

(21) Sample concentration: 1 mg/mL, 20 μL injection

(22) Standard samples: polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485)

(23) 2. NMR analysis

(24) The NMR analysis was performed at room temperature using an NMR spectrometer including a Varian Unity Inova (500 MHz) spectrometer with a triple resonance 5 mm probe. An analyte was diluted in a solvent (CDC13) for measuring NMR 23 to a concentration of about 10 mg/ml and used, and chemical shifts were expressed in ppm.

(25) <Application Abbreviations>

(26) br=wide signal, s=singlet, d=doublet, dd=double doublet, t=triplet, dt=double triplet, q=quartet, p=quintet, m=muliplet.

PREPARATION EXAMPLE 1

Synthesis of Monomer (A)

(27) The compound (DPM-C12) of Formula A below was synthesized in the following manner. Hydroquinone (10.0 g, 94.2 mmol) and 1-bromododecane (23.5 g, 94.2 mmol) were placed in a 250 mL flask, dissolved in 100 mL of acetonitrile, and then an excess amount of potassium carbonate was added thereto and reacted at 75° C. for about 48 hours under a nitrogen condition. After the reaction, the remaining potassium carbonate was filtered off and the acetonitrile used in the reaction was also removed. A mixed solvent of DCM (dichloromethane) and water was added thereto to work up the mixture, and the separated organic layers were collected and passed through MgSO .sub.4 to be dehydrated. Subsequently, the target product (4-dodecyloxyphenol) (9.8 g, 35.2 mmol) in a white solid phase was obtained in a yield of about 37% using dichloromethane in column chromatography.

(28) The synthesized 4-docecyloxyphenol (9.8 g, 35.2 mmol), methacrylic acid (6.0 g, 69.7 mmol), DCC (dicyclohexylcarbodiimide) (10.8 g, 52.3 mmol) and DMAP (p-dimethylaminopyridine) (1.7 g, 13.9 mmol) were placed in the flask and 120 mL of methylene chloride was added thereto, and then reacted at room temperature for 24 hours under nitrogen. After completion of the reaction, the salt (urea salt) generated during the reaction was filtered off and the remaining methylene chloride was also removed. Impurities were removed using hexane and DCM (dichloromethane) as the mobile phase in column chromatography and the product obtained again was recrystallized in a mixed solvent of methanol and water (1:1 mix) to obtain the target product (7.7 g, 22.2 mmol) in a white solid phase in a yield of 63%.

(29) ##STR00005##

(30) In Formula A, R is a linear alkyl group having 12 carbon atoms.

(31) <NMR analysis results of monomer (A)>

(32) 1H-NMR (CDC13): d7.02 (dd, 2H); d6.89 (dd, 2H); d6.32 (dt, 1H); d5.73 (dt, 1H); d3.94 (t, 2H); d 2.05(dd, 3H); d1.76 (p, 2H); d1.43 (p, 2H); 1.34-1.27 (m, 16H); d0.88 (t, 3H).

PREPARATION EXAMPLE 2

Synthesis of Random Copolymer (B)

(33) 0.5340 g of the compound (DPM-C12) of Preparation Example 1, 1.1367 g of pentafluorostyrene, 30.0 mg of an RAFT (reversible addition-fragmentation chain transfer) agent (2-hydroxyethyl 2-((dodecylthio)carbonothioyl)thio)-2-methylpropanoate), 5.1 mg of AIBN (azobisisobutyronitrile) and 1.67 mL of anisole were placed in a 10 mL flask (Schlenk flask), stirred at room temperature for 30 minutes under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) was performed at 70° C. for 12 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then dried after filtering under reduced pressure to prepare a random copolymer. The number average molecular weight (Mn) and the molecular weight distribution (Mw/Mn) of the random copolymer were 12,300 and 1.17, respectively.

PREPARATION EXAMPLE 3

Synthesis of block copolymer (A-1)

(34) 2.0 g of the monomer (A) of Preparation Example 1, 64 mg of cyanoisoproyl dithiobenzoate as an RAFT (reversible addition-fragmentation chain transfer) reagent, 23 mg of AIBN (azobisisobutyronitrile) as a radical initiator and 5.34 mL of benzene were placed in a 10 mL Schlenk flask and stirred at room temperature for 30 minutes under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 70° C. for 4 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pink macro initiator. The yield of the macro initiator was about 82.6 wt % and the number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were 9,000 and 1.16, respectively. 0.3 g of the macro initiator, 2.7174 g of a pentafluorostyrene monomer and 1.306 mL of benzene were placed in a 10 mL Schlenk flask and stirred at room temperature for 30 minutes under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 115° C. for 4 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pale pink block copolymer. The block copolymer comprises a polymer segment A, which is derived from the monomer (A) of Preparation Example 1 and has 12 chain-forming atoms (the number of carbon atoms of R in Formula A), and a polymer segment B derived from the pentafluorostyrene monomer.

PREPARATION EXAMPLE 4

Synthesis of Block Copolymer (A-2)

(35) 4.0 g of the monomer (A) of Preparation Example 1, 10.9 mg of cyanoisoproyl dithiobenzoate as an RAFT (reversible addition-fragmentation chain transfer) reagent, 4 mg of AIBN (azobisisobutyronitrile) as a radical initiator and 9.3 g of anisole were placed in a 20 mL Schlenk flask and stirred at room temperature for 30 minutes under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 70° C. for 4 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pink macro initiator. The yield of the macro initiator was about 75 wt % and the number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were 33,100 and 1.25, respectively. 0.5 g of the macro initiator, 3.225 g of a pentafluorostyrene monomer, 1.2 mg of AIBN and 1.248 mL of anisole were placed in a 10 mL Schlenk flask and stirred at room temperature for 1 hour under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 70° C. for 6 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pale pink block copolymer. The block copolymer comprises a polymer segment A, which is derived from the monomer (A) of Preparation Example 1 and has 12 chain-forming atoms (the number of carbon atoms of R in Formula A), and a polymer segment B derived from the pentafluorostyrene monomer.

PREPARATION EXAMPLE 5

Synthesis of Block Copolymer (A-3)

(36) 2.0 g of the monomer (A) of Preparation Example 1, 85 mg of cyanoisoproyl dithiobenzoate as an RAFT (reversible addition-fragmentation chain transfer) reagent, 31 mg of AIBN (azobisisobutyronitrile) as a radical initiator and 4.5 g of anisole were placed in a 20 mL Schlenk flask and stirred at room temperature for 30 minutes under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 70° C. for 4 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pink macro initiator. The yield of the macro initiator was about 63 wt % and the number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were 7,100 and 1.16, respectively. 0.3 g of the macro initiator, 1.312 g of a pentafluorostyrene monomer, 3.5 mg of AIBN and 0.540 mL of anisole were placed in a 10 mL Schlenk flask and stirred at room temperature for 1 hour under a nitrogen atmosphere, and then an RAFT (reversible addition-fragmentation chain transfer) polymerization reaction was performed at 70° C. for 4 hours. After the polymerization, the reaction solution was precipitated in 250 mL of methanol as an extraction solvent, and then filtered under reduced pressure and dried to prepare a pale pink block copolymer. The block copolymer comprises a polymer segment A, which is derived from the monomer (A) of Preparation Example 1 and has 12 chain-forming atoms (the number of carbon atoms of R in Formula A), and a polymer segment B derived from the pentafluorostyrene monomer.

EXAMPLE 1

(37) The random copolymer (B) of Preparation Example 2 was coated on a silicon wafer substrate to a thickness of about 40 nm and subjected to thermal annealing at 160° C. for 24 hours to form a polymer membrane. The substrate on which the polymer membrane was formed was subjected to sonication in fluorobenzene for about 10 minutes or so to remove unreacted materials. Subsequently, a block copolymer membrane was formed on the substrate, on which the random copolymer membrane was formed, using the block copolymer (A-1) of Preparation Example 3. Specifically, a coating solution prepared by diluting the block copolymer (A-1) to a solid content concentration of about 1.5 wt % in fluorobenzene was spin-coated on the substrate to a thickness of about 60 nm, dried at room temperature for about 1 hour and then thermally annealed at a temperature of about 160° C. for about 1 hour to form a self-assembled block copolymer membrane. FIG. 1 is an SEM (scanning electron microscope) image of the formed membrane. As could be seen in FIG. 1, the block copolymer formed vertically oriented lamellar patterns highly self-aligned on the polymer membrane, and the pitch was about 31 nm or so. The self-assembled block copolymer membrane was subjected to plasma etching.

(38) Specifically, the substrate on which the polymer membrane and the block copolymer membrane were sequentially formed was introduced into an etching chamber. In the etching chamber, two parallel plate electrodes were present facing each other, where the substrate on which the block copolymer membrane was formed was positioned on the electrode to which RF power to be described below was applied between the two electrodes. Subsequently, in a state where the process pressure in the etching chamber was maintained at about 15 mTorr, the RF power of 300 W was applied to the electrode that the block copolymer membrane was positioned thereon to perform etching. The etching was performed while feeding perfluorobutane (C.sub.4F.sub.8), argon (Ar) and oxygen (O.sub.2), as process gases, at flow rates of 15 sccm, 100 sccm and 25 sccm, respectively, into the chamber, where the etching time was 40 seconds or so. FIG. 2 shows the results of the etching performed as above. As confirmed from FIG. 2, in the case of the etching conditions of the example, the domain formed by one segment of the block copolymer was selectively removed.

EXAMPLE 2

(39) The etching was performed under the same conditions as those of Example 1, except that fluoroform (CHF.sub.3) and oxygen (O.sub.2) as process gases were supplied at flow rates of 40 sccm and 10 sccm, respectively, into the etching chamber and the etching time was adjusted to 45 seconds or so. FIG. 3 is an SEM image showing the etching result of Example 2. Through FIG. 3, it can be confirmed that the domain formed by one segment of the block copolymer can be selectively removed by performing the etching under the above conditions.

EXAMPLE 3

(40) A coating solution prepared by mixing the block copolymer (A-2) of Preparation Example 4 and the block copolymer (A-3) of Preparation Example 5 at a ratio of 70/30 (parts by weight/weight), respectively and then diluting the mixture to a solid content concentration of about 1.2 wt % in fluorobenzene was spin-coated on a silicon wafer substrate to a thickness of about 50 nm, dried at room temperature for about 1 hour and then again thermally annealed at a temperature of about 180° C. for about 1 hour to form a self-assembled block copolymer membrane. SEM (scanning electron microscope) imaging was performed on the formed block copolymer membrane. FIG. 4 is an SEM (scanning electron microscope) image of the formed block copolymer membrane. As in the drawing, the block copolymer formed vertically oriented lamellar patterns highly aligned in the block copolymer membrane, and the pitch was about 37 nm or so. Plasma etching was performed on the polymer membrane comprising the assembled block copolymer. The etching was performed in the same manner as in Example 1 in the same etching chamber as that of Example 1, where the process pressure was about 15 mTorr or so and the etching was performed by applying RF power of 200 W or so. Perfluorobutane (C.sub.4F.sub.8), an argon (Ar) gas and oxygen (O.sub.2) as process gases were fed into the chamber at flow rates of 15 sccm, 100 sccm and 25 sccm, respectively, and the etching time was about 35 seconds or so. FIG. 5 shows the results of the etching performed as above. As confirmed from FIG. 5, in the case of the etching conditions of the example, the domain formed by one segment of the block copolymer was selectively removed.

EXAMPLE 4

(41) Plasma etching for pattern transferring the pattern of the block copolymer onto the substrate was performed by further etching the substrate using the membrane of the etched block copolymer of Example 2 as a mask. The pressure in the etching chamber was maintained at 50 mTorr, the RF power was maintained at 80 W, the flow rate of SF.sub.6 supplied to the chamber was maintained at 45 sccm, and the etching time was maintained at 15 seconds.

(42) This pattern transfer result was shown in FIG. 6. As confirmed from FIG. 6, when the pattern is transferred onto the substrate using the etched block copolymer membrane of Example 2 as a mask, it can be confirmed that the pattern on the silicon substrate is well formed according to the pattern formed by the block copolymer.

COMPARATIVE EXAMPLE 1

(43) Etching of the block copolymer membrane was performed in the same manner as in Example 1, except that fluoroform (CHF.sub.3) and oxygen (O.sub.2) as process gases were supplied at flow rates of 40 sccm and 2 sccm, respectively, into the etching chamber, the applied RF power was 200 W, and the etching time was adjusted to 45 seconds or so.

(44) FIG. 7 is an SEM image showing the etching result of Comparative Example 1. Through FIG. 7, it can be confirmed that as a result of performing the etching under the above conditions, the domain formed by one segment of the block copolymer cannot be selectively removed.

COMPARATIVE EXAMPLE 2

(45) Etching of the block copolymer membrane was performed in the same manner as in Example 1, except that fluoroform (CHF.sub.3) and oxygen (O.sub.2) as process gases were supplied at flow rates of 40 sccm and 5 sccm, respectively, into the etching chamber, the applied RF power was 100 W, and the etching time was adjusted to 45 seconds or so.

(46) FIG. 8 is an SEM image showing the etching result of Comparative Example 2. Through FIG. 8, it can be confirmed that as a result of performing the etching under the above conditions, the domain formed by one segment of the block copolymer cannot be selectively removed.

COMPARATIVE EXAMPLE 3

(47) Etching of the block copolymer membrane was performed in the same manner as in Example 3, except that argon (Ar) and oxygen (O.sub.2) as process gases were supplied at flow rates of 25 sccm and 10 sccm, respectively, into the etching chamber, the applied RF power was 50 W, and the etching time was adjusted to 30 seconds or so.

(48) FIG. 9 is an SEM image showing the etching result of Comparative Example 3. Through FIG. 9, it can be confirmed that as a result of performing the etching under the above conditions, the segment of the block copolymer forming the matrix is not completely removed.

COMPARATIVE EXAMPLE 4

(49) Etching of the block copolymer membrane was performed in the same manner as in Example 1, except that fluoroform (CHF.sub.3) and oxygen (O.sub.2) as process gases were supplied at flow rates of 5 sccm and 15 sccm, respectively, into the etching chamber, the applied RF power was 100 W, and the etching time was adjusted to 45 seconds or so.

(50) FIG. 10 is an SEM image showing the etching result of Comparative Example 4. Through FIG. 10, it can be confirmed that as a result of performing the etching under the above conditions, the domain formed by one segment of the block copolymer cannot be selectively removed.

COMPARATIVE EXAMPLE 5

(51) Etching of the block copolymer membrane was performed in the same manner as in Example 1, except that fluoroform (CHF.sub.3) and oxygen (O.sub.2) as process gases were supplied at flow rates of 38 sccm and 5 sccm, respectively, into the etching chamber, the applied RF power was 100 W, and the etching time was adjusted to 45 seconds or so.

(52) FIG. 11 is an SEM image showing the etching result of Comparative Example 5. Through FIG. 11, it can be confirmed that as a result of performing the etching under the above conditions, the domain formed by one segment of the block copolymer cannot be selectively removed.

EXPLANATION OF REFERENCE NUMERALS

(53) 10: anode 20: cathode 30: substrate on which a block copolymer membrane is formed

(54) 40: RF power source

(55) 50: reaction gas 50′: reaction gas in a plasma state

(56) 51: electron 51′: ion sheath or ion shell

(57) 52: ion of reaction gas

(58) 53: radical of reaction gas

(59) 100: reaction chamber