US20040079730A1 - Plastic male mold for fabricating microstructures and nanostructures using imprint lithography - Google Patents

Plastic male mold for fabricating microstructures and nanostructures using imprint lithography Download PDF

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Publication number
US20040079730A1
US20040079730A1 US10/433,589 US43358903A US2004079730A1 US 20040079730 A1 US20040079730 A1 US 20040079730A1 US 43358903 A US43358903 A US 43358903A US 2004079730 A1 US2004079730 A1 US 2004079730A1
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fact
structures
consist
photo
male mold
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US10/433,589
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Gisel Ahrens
Gabi Gruetzner
Karl Pfeiffer
Freimuth Reuther
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Micro Resist Technology GmbH
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Micro Resist Technology GmbH
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Assigned to MICRO RESIST TECHNOLOGY GMBH. reassignment MICRO RESIST TECHNOLOGY GMBH. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AHRENS, GISELA, GRUETZNER, GABI, PFEIFFER, KARL, TEUTHER, FREIMUTH
Publication of US20040079730A1 publication Critical patent/US20040079730A1/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0017—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor for the production of embossing, cutting or similar devices; for the production of casting means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping

Definitions

  • the invention describes the fabrication and use of lithographically produced resist structures used as mold material for imprint lithography for fabricating micro and nanostructures.
  • the structural layout imprinted directly on the resist layers must be transferred to more stable materials by several partial steps, such as plasma etching and galvanizing (Semi-Conductor Lithography, Principles, Practices, and Materials; W. M. Moreau, Plenium Press, New York, 1988).
  • the structure transfer of nano-scaled resist structures to more stable inorganic materials poses a number of problems.
  • the plasma etching resistance of conventional hyper-sensitive electron beam resists is insufficient, and their galvanic copying process places special demands on the profile of the structure, and on the thermal stability and solubility of the resist structures (Introduction to Microlithography; L. E. Thompson et al., ACS Professional Reference Book, American Chemical Society, Washington D.C., 1994).
  • This may usually be realized by combinations of different polymers or by using special auxiliary layers in multiple-layer systems and necessitates further partial steps and, therefore, a loss of precision and resolution of the structures.
  • the object is accomplished by use of a negative system the lithographically fabricated structures of which satisfy the demands placed on a mold for embossing thin polymeric layers.
  • mixtures of photo-reactive epoxy resins are preferably used for fabricating a master structure.
  • they are multi-functional aromatic, hetero-aromatic, aliphatic and cyclo-aliphatic epoxy resins and include photo-initiators.
  • the masks are preferably made by optical lithography, and for nano-structuring they are made by electron beam lithography.
  • the sensitivity of the used materials against ultraviolet light and high-energy radiation makes it possible to increase their structural stability by subjecting their surface to ultraviolet irradiation and by thermal after-treatment of the developed structures.
  • the high degree of cross-linking prevents thermal flow up to the thermal decomposition temperature of the polymers at about 200° C.
  • the embossing temperatures of many polymers lie substantially below this temperature. It is particularly advantageous if the layer to be embossed also consists of a curable material based on a photo-reactive epoxy resin.
  • the embossing process may be carried out in a manner similar to the one used in connection with thermoplastic polymers. In the absence of UV radiation, cross-linking is substantially prevented at temperatures up to 180° C.
  • the preferred embossing temperatures lie in the range of 60-140° C., preferably 80-120° C., at an embossing pressure in the range of 40-100 bar, preferably 60-80 bar.
  • Structural profiles of excellent thermal and mechanical stability are attained, separate from the embossing tool, by subsequent UV surface irradiation and thermal after-processing at up to 150° C.
  • the embossed structures may thus also be used as molds.
  • the surface UV irradiation may be carried out by a high pressure mercury lamp.
  • the preferred dosage is in the range of 100-1000 mJ/cm 2 .
  • Thermal processing may take place at a temperature up to 200° C., without any thermal decomposition of the cross-linked polymer being noticeable.
  • photo-reactive epoxy systems it is, of course, also possible to emboss other thin-layered polymers.
  • examples of such polymers are thermoplastic polymers having a glass temperature of ⁇ 150° C., and curable pre-polymers. The thermal stability of most mold materials lies at about 200° C.
  • the principle of the structure transfer is shown schematically in the figure.
  • the master structure fabricated in a resist by electron beam lithography is embossed (1) under pressure and temperature, into a coated material. This results in a negative image of the mold (2) used.
  • the polymer layer to be embossed consists of photo-reactive epoxy resins
  • the embossed image may also be used as a mold (3) which then results in the original structural layout of the initial mold (4).
  • UV surface irradiation and thermal after-processing are performed to yield the required stability.
  • a 4 inch silicon wafer was coated at a rotational velocity of 4,000 rpm with a resist material mr-L-6000.1 of the company micro resist technology GmbH (basic material photo-reactive epoxy resins) and subsequently thermally treated for 3 minutes on a heating plate at 90° C.
  • the layer had a thickness of 100 nm.
  • the desired structure was inscribed with an electron stylus at an energy of 30 kV and a dosage of 5 ⁇ C/cm 2 and developed by processing in PGMEA. Thereafter, the developed structure was irradiated by UV light at a dosage of 1,000 mJ/cm 2 and then thermally after-processed on a heating plate at 150° C.
  • the fabricated resist mask was subsequently embossed into a polymeric layer of 300 nm thickness and consisting of the same resist system (mr-L6000.5), at an embossing temperature of 80° C. and pressure 60 bar.
  • the use of perfluoro octyl silane as a separation agent results in a separation without any problems.
  • the quality of the imprint corresponded to the structure of the male mold. The smallest structure resolution was about 30 nm.

Abstract

Known electron beam lithography used for manufacturing male molds is cost-intensive and very time consuming. As a result, conventional highly sensitive electron beam resists have an insufficient plasma etching resistance and galvanic molding makes special demands on the structural profile and the thermal stability and solubility of the resist structures. The novel production and use of lithographically produced resist structures as male mold material for use in imprint lithography for producing microstructures and nanostructures should thus overcome the drawbacks associated with the conventional procedure for producing male molds. To this end, a negative resist system is used whose lithographically produced structures correspond to the demands made on a male mold for molding thin polymer layers. Lithographically produced structures comprised of curable materials are thus used for molding, preferably those based on photo-reactive epoxy resins. The invention, in turn, enables an economical and thereby low-cost production of male mold material.

Description

  • The invention describes the fabrication and use of lithographically produced resist structures used as mold material for imprint lithography for fabricating micro and nanostructures. [0001]
    • THE STATE OF THE ART
  • Structures dimensioned on the nanometer scale may be economically fabricated in large numbers by imprint lithography. (S. Y. Chou et al. Vac. Sci. Technol. B 15(6) (1997), 2897; U.S. Pat. No. 5,772,905). In this context, cost-intensive and time consuming electron beam lithography is used only for fabricating the mold. A large number of imprints may then be produced with the fabricated molds by thermal embossing of layers of polymeric materials on different substrates. The properties of the electron beam resists hitherto available do not, however, permit their direct use as molds. Following its development process, the structural layout imprinted directly on the resist layers must be transferred to more stable materials by several partial steps, such as plasma etching and galvanizing (Semi-Conductor Lithography, Principles, Practices, and Materials; W. M. Moreau, Plenium Press, New York, 1988). The structure transfer of nano-scaled resist structures to more stable inorganic materials poses a number of problems. The plasma etching resistance of conventional hyper-sensitive electron beam resists is insufficient, and their galvanic copying process places special demands on the profile of the structure, and on the thermal stability and solubility of the resist structures (Introduction to Microlithography; L. E. Thompson et al., ACS Professional Reference Book, American Chemical Society, Washington D.C., 1994). This may usually be realized by combinations of different polymers or by using special auxiliary layers in multiple-layer systems and necessitates further partial steps and, therefore, a loss of precision and resolution of the structures. [0002]
  • It is an object of the present invention to overcome the disadvantages inherent in conventional processes of mold fabrication. [0003]
  • In accordance with the invention, the object is accomplished by use of a negative system the lithographically fabricated structures of which satisfy the demands placed on a mold for embossing thin polymeric layers. [0004]
  • The details of the method in accordance with the invention are as follows. In the context of the invention, mixtures of photo-reactive epoxy resins are preferably used for fabricating a master structure. In general, they are multi-functional aromatic, hetero-aromatic, aliphatic and cyclo-aliphatic epoxy resins and include photo-initiators. For micro-structuring, the masks are preferably made by optical lithography, and for nano-structuring they are made by electron beam lithography. The sensitivity of the used materials against ultraviolet light and high-energy radiation makes it possible to increase their structural stability by subjecting their surface to ultraviolet irradiation and by thermal after-treatment of the developed structures. This results in complete hardening, and the stability attained by the structures renders them suitable as embossing tools. The high degree of cross-linking prevents thermal flow up to the thermal decomposition temperature of the polymers at about 200° C. The embossing temperatures of many polymers lie substantially below this temperature. It is particularly advantageous if the layer to be embossed also consists of a curable material based on a photo-reactive epoxy resin. The embossing process may be carried out in a manner similar to the one used in connection with thermoplastic polymers. In the absence of UV radiation, cross-linking is substantially prevented at temperatures up to 180° C. Because of the low glass temperature and molar mass of such systems, the preferred embossing temperatures lie in the range of 60-140° C., preferably 80-120° C., at an embossing pressure in the range of 40-100 bar, preferably 60-80 bar. Structural profiles of excellent thermal and mechanical stability are attained, separate from the embossing tool, by subsequent UV surface irradiation and thermal after-processing at up to 150° C. The embossed structures may thus also be used as molds. The surface UV irradiation may be carried out by a high pressure mercury lamp. [0005]
  • The preferred dosage is in the range of 100-1000 mJ/cm[0006] 2. Thermal processing may take place at a temperature up to 200° C., without any thermal decomposition of the cross-linked polymer being noticeable. Instead of photo-reactive epoxy systems, it is, of course, also possible to emboss other thin-layered polymers. Examples of such polymers are thermoplastic polymers having a glass temperature of <150° C., and curable pre-polymers. The thermal stability of most mold materials lies at about 200° C.
  • The principle of the structure transfer is shown schematically in the figure. The master structure fabricated in a resist by electron beam lithography is embossed (1) under pressure and temperature, into a coated material. This results in a negative image of the mold (2) used. Where the polymer layer to be embossed consists of photo-reactive epoxy resins, the embossed image may also be used as a mold (3) which then results in the original structural layout of the initial mold (4). In order to increase the thermal and mechanical stability, following each embossing step, UV surface irradiation and thermal after-processing are performed to yield the required stability. [0007]
    Figure US20040079730A1-20040429-C00001
  • Without claiming completeness, the following examples will describe the invention in greater detail.[0008]
    • EXAMPLE 1.
  • Structure transfer in thin polymeric layers. [0009]
  • Fabrication of the layout of the mold: [0010]
  • A 4 inch silicon wafer was coated at a rotational velocity of 4,000 rpm with a resist material mr-L-6000.1 of the company micro resist technology GmbH (basic material photo-reactive epoxy resins) and subsequently thermally treated for 3 minutes on a heating plate at 90° C. The layer had a thickness of 100 nm. The desired structure was inscribed with an electron stylus at an energy of 30 kV and a dosage of 5 μC/cm[0011] 2 and developed by processing in PGMEA. Thereafter, the developed structure was irradiated by UV light at a dosage of 1,000 mJ/cm2 and then thermally after-processed on a heating plate at 150° C. The fabricated resist mask was subsequently embossed into a polymeric layer of 300 nm thickness and consisting of the same resist system (mr-L6000.5), at an embossing temperature of 80° C. and pressure 60 bar. The use of perfluoro octyl silane as a separation agent results in a separation without any problems. The quality of the imprint corresponded to the structure of the male mold. The smallest structure resolution was about 30 nm.
    • EXAMPLE 2
  • The resist structure fabricated in example 1 and its copy were used in nano imprint lithography for embossing the structure (table). Compared to a SiO[0012] 2—mold no differences in quality resulted in copying the structure.
    Polymer Layer Embossing Embossing
    Mold D = 300 nm Temperature (° C.) Pressure (bar)
    SiO2 mr-I 80301 180 100
    SiO2 mr-I 8030 180 100
    Resist structure mr-I 8030 180 100
    Copy mr-I 8030 180 100
    Resist structure mr-I 90302 160 100
    Copy mr-I 9030 160 100
    Resist structure mr-L 6000.53 80 80
    Copy mr-L 6000.5 80 80
    Resist structure PMMA 180 100
    Copy PMMA 180 100

Claims (10)

1. The invention relates to the fabrication of micro and nano structures by heat embossing, characterized by the fact that for copying lithographically produced structures are used which consist of curable materials, preferably based on photo-reactive epoxy resins and the structure transfer is preferably carried out in thin layers.
2. according to claim 1 characterized by the fact that preferably structured resist layers based on photo-reactive aliphatic, aromatic, cyclo-aliphatic epoxy resins and mixtures thereof are used.
3. according to claim 1 characterized by the fact that the master structures used for the micrometer range are preferably fabricated by optical lithography and for the nanometer range in particular are fabricated by electron beam lithography.
4. According to claim 1 characterized by the fact that the structure transfer is preferably carried out in polymeric layers the layer thicknesses of which are less than 1 micrometer.
5. according to claim 3 characterized by the fact that following the development process the master structures are after-treated by UV surface irradiation in the dosage range of 200-2,000 mJ/cm2, preferably between 500-1,000 mJ/cm2 and at a temperature of 50-180° C., preferably between 120-150° C.
6. according to claim 1 characterized by the fact that the layers to be embossed consist of thermoplastic polymers the glass temperatures of which preferably are below 150° C.
7. according to claim 1 characterized by the fact that the layers to be embossed consist of curable polymers.
8. according to claim 6 characterized by the fact that the curable polymers preferably consist of photo-reactive epoxy resins.
9. according to claim 6 characterized by the fact that the curable polymers preferably consist of cross-linkable allyl polymers.
10. according to claim 7 characterized by the fact that after hardening the embossed structures are used as embossing tools.
US10/433,589 2001-07-05 2002-06-28 Plastic male mold for fabricating microstructures and nanostructures using imprint lithography Abandoned US20040079730A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10134763A DE10134763A1 (en) 2001-07-05 2001-07-05 Plastic stamp for the production of micro and nanostructures with imprint lithography
DE10134763.4 2001-07-05
PCT/DE2002/002435 WO2003005123A2 (en) 2001-07-05 2002-06-28 Method for the production of microstructures and nanostructures using imprint lithography

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050274693A1 (en) * 2004-05-07 2005-12-15 Babak Heidari Device and method for lithography
US20070018362A1 (en) * 2003-12-05 2007-01-25 Babak Heidari Device and method for large area lithography
US20080006273A1 (en) * 2006-07-06 2008-01-10 Thornton W Keith System and Method for Forming a Custom Medical Mask from a Three-Dimensional Electronic Model
US8846551B2 (en) 2005-12-21 2014-09-30 University Of Virginia Patent Foundation Systems and methods of laser texturing of material surfaces and their applications
US10131086B2 (en) 2011-06-30 2018-11-20 University Of Virginia Patent Foundation Micro-structure and nano-structure replication methods and article of manufacture

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007046110A1 (en) * 2005-10-19 2007-04-26 Indian Institute Of Technology, Kanpur A method and apparatus for the formation of patterns on surfaces and an assembly and alignment of the structure thereof
DE102019101346A1 (en) 2019-01-18 2020-07-23 Osram Opto Semiconductors Gmbh NANOSTAMPING PROCESS AND NANOOPTIC COMPONENT

Citations (2)

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US5772905A (en) * 1995-11-15 1998-06-30 Regents Of The University Of Minnesota Nanoimprint lithography
US5874041A (en) * 1996-05-30 1999-02-23 Dsm N.V. Photo-curable resin composition and process for preparing resin-based mold

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1072954A3 (en) * 1999-07-28 2002-05-22 Lucent Technologies Inc. Lithographic process for device fabrication
DE10030015A1 (en) * 2000-06-17 2002-01-24 Micro Resist Technology Gmbh Material used for nano-imprint lithography for producing embossed nano-structure in thin film on substrate, useful as embossing tool for thermoplastics, is curable and embossed above glass transition temperature

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5772905A (en) * 1995-11-15 1998-06-30 Regents Of The University Of Minnesota Nanoimprint lithography
US5874041A (en) * 1996-05-30 1999-02-23 Dsm N.V. Photo-curable resin composition and process for preparing resin-based mold

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070018362A1 (en) * 2003-12-05 2007-01-25 Babak Heidari Device and method for large area lithography
US8147235B2 (en) 2003-12-05 2012-04-03 Obducat Ab Device and method for large area lithography
US20050274693A1 (en) * 2004-05-07 2005-12-15 Babak Heidari Device and method for lithography
US20070164487A1 (en) * 2004-05-07 2007-07-19 Marc Beck Method for imprint lithography at constant temperature
US20080030700A1 (en) * 2004-05-07 2008-02-07 Obducat Ab Device and method for lithography
US7972553B2 (en) * 2004-05-07 2011-07-05 Obducat Ab Method for imprint lithography at constant temperature
US7997890B2 (en) 2004-05-07 2011-08-16 Obducat Ab Device and method for lithography
US8846551B2 (en) 2005-12-21 2014-09-30 University Of Virginia Patent Foundation Systems and methods of laser texturing of material surfaces and their applications
US20080006273A1 (en) * 2006-07-06 2008-01-10 Thornton W Keith System and Method for Forming a Custom Medical Mask from a Three-Dimensional Electronic Model
US8874251B2 (en) * 2006-07-06 2014-10-28 Airway Technologies, Llc System and method for forming a custom medical mask from a three-dimensional electronic model
US10131086B2 (en) 2011-06-30 2018-11-20 University Of Virginia Patent Foundation Micro-structure and nano-structure replication methods and article of manufacture

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WO2003005123A2 (en) 2003-01-16
EP1402317A2 (en) 2004-03-31
WO2003005123A3 (en) 2003-07-31
DE10134763A1 (en) 2003-01-16

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