Classifications

• • 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 present invention relates to the removal of thin, structured polymer layers, in particular the removal of thin residual layers, which were formed by a stamp or imprint method.
• a method for so-called imprint lithography is described, for example, in US Pat. No. 5,772,905.
• a mold is pressed into a thin resist layer deposited on a substrate.
• structures formed on the mold are introduced into the photoresist layer.
• the substrate is etched and thus the structure located on the mold is introduced into the substrate.
• US-A-5 772 905 describes the use of a thermoplastic polymer.
• a radiation-polymerizable fluid is possible, as described for example in WO 00/54107.
• the curing of the polymerizable fluid is not effected as in the case of thermoplastic polymers by cooling but by the action of radiation.
• US-A-5,772,905 the removal of the residual layer remaining in the regions of the structure in which the mold comes approximately in contact with the substrate, by ion etching or wet chemical etching, is described.
• Removing this residual layer is necessary for subsequent process steps, that is, for example, the etching of the substrate.
• a structure in a resist layer applied to a substrate is advantageously formed by pressing a mold into the resist layer.
• the mold has at least one projection which, when the mold is pressed onto the substrate in the region of this projection, comes approximately in contact with the substrate and thus approximately removes the material forming the resist layer in this region.
• the resist layer to be structured has, for example, a polymer which is thermoplastic or radiation-curable.
• the layer is made deformable by heating, thereby enabling the stamping of the structure. By cooling, the polymer layer is subsequently cured.
• the material is applied in nearly liquid form to the substrate and irradiated for curing during the stamping process.
• the resist layer remaining in the area of a valley or valley formed by a protrusion of the mold in the resist layer is removed by means of a plasma at atmospheric pressure.
• the atmospheric plasma formed by a corresponding gas is preferably generated by a corona discharge or a plasma barrier discharge (DBD). Suitable process gases are, for example, O 2 or O 2 / CF 4 .
• the advantage of the present invention is the replacement of the reactive ion etching (RIE) process commonly used in the art by the simple and inexpensive treatment with atmospheric plasma. In the treatment with atmospheric plasma further heating of the substrates and the damage of temperature-sensitive substrates is avoided.
• RIE reactive ion etching
• the plasma generation preferred by the invention by means of corona discharge the electric barrier discharge
• a multiplicity of localized microdischarges are formed between two conducting electrodes when the alternating voltage of sufficient magnitude is applied, which have a very short period of time in the range of 10.sup.s.sec
• the average gas temperature in the discharge gap is thus only increased by a few degrees Kelvin.
• the discharge remains cold.
• Another advantage over the prior art proposed or used methods is the avoidance of the risk of damage or contamination of the substrate.
• FIGS. 1 to 4 (a) and 4 (b) the method steps of the method according to the invention
• Figures 5 (a) and 5 (b) show cross-sectional electrode arrangements suitable for producing an atmospheric plasma according to the invention.
• FIGS. 6 (a) and 6 (b) show measurements of the layer thickness of a residual layer before and after the application of the method according to the invention.
• FIG. 1 shows a substrate 1 which is coated with a still deformable resist layer 2 into which structures are to be introduced. Furthermore, a mold or a stamp 3 is shown which has structures on one side. In general, these structures are formed by protrusions 31 and depressions 32. The structure widths can be on the order of several micrometers, but also in the nanometer range.
• the mold 3 is pressed into the deformable resist layer 2 after the mold 3 is optionally aligned with the substrate 1 by means of an alignment device (not shown).
• an alignment device not shown
• the mold 3 in the region of the projections 31, the mold 3 almost comes into contact with the substrate 1, so that only a thin residual layer remains between the mold 3 and the substrate 1 in this region.
• the resist layer 2 is acted upon so that it solidifies. This can be done, for example, by cooling in the case of a thermoplastic polymer.
• the resist layer 2 is solidified by irradiation with, for example, UV rays ("cold embossing"). In this case, however, at least either the mold 3 or the substrate 1 must be permeable to the radiation used be. In so-called "hot embossing", the resist layer 2 is solidified by the action of pressure and high temperature.
• the mold 3 is removed (see Fig. 3).
• a negative impression of the structures of the mold 3 is formed.
• the intended structures 21 are formed at locations where the mold 3 has depressions 32.
• Projections 31 valleys formed only a thin residual layer 22 is present.
• the thickness of the residual layer in the range of a few to several hundred nanometers.
• This residual layer 22 is removed, as shown in FIGS. 4 a and 4 b, by the action of an atmospheric plasma 5, 5 '.
• the principles of the atmospheric plasma treatment are described, for example, in DE-A-102 56 693.
• the plasma 5, 5 ' is generated below a high voltage electrode 4 from a process gas, for example O 2 or CF 4 .
• the electrode 4 may be arranged as a surface electrode stationary over the entire surface of the substrate 1 with the cured resist layer 2 '. Alternatively, the electrode 4 can be moved with respect to the substrate 1, and thus pass through the surface of the substrate 1. For example, a linear electrode can be guided over the surface of the substrate 1. Radicals that form in the plasma 5, 5 'react with organic surfaces, decompose them and carry off the resulting gaseous products through the purge gas.
• FIG. 4a shows the case in which the plasma 5 is formed under the entire surface of the electrode
• FIG. 4b shows an alternative situation in which only in the regions in which the thin residual layer 22 is to be removed, a plasma 5 'is formed.
• the breakdown voltage is higher than the breakdown voltage of the residual layer 22 but lower than the breakdown voltage of the structure 21, it may be indicated by the breakdown voltage shown in FIG. 4b
• FIG. 5 (a) and (b) show the cross-section of an electrode assembly suitable for producing an atmospheric plasma according to the invention.
• the electrodes 41 and 42 shown represent linear electrodes which extend into the plane of the drawing and can be moved to extend the entire surface of the substrate 1 in the plane of the drawing.
• Fig. 5 (a) there is shown the case where discharge takes place directly between the substrate 1 and the electrodes 41 and 42, respectively. In this area, therefore, forms a plasma 51 and 52, which is also referred to as "direct plasma".
• the substrate 1 may be regarded as a capacitor plate which is at a floating potential. This process is strongly influenced by the distance between substrate and electrode.
• the plasma 53 ignites between the electrodes 41 and 42 ("remote plasma"). Resulting gas radicals are transported to the substrate in the air gap 6 and react with the surface of the substrate 1. By suitable means (not shown) on the electrode system is prevented that a direct discharge on the substrate 1 takes place.
• Both systems shown in Figure 5 (a) and (b) also have a gas supply 7 and a gas extraction 8, which ensure the continuous gas exchange in the process area.
• the effect of the direct plasma process is more effective, but here the parameters must be carefully selected to avoid damage to the surface of the substrate.
• a circular recess was stamped into a UV curable resist layer by the method described above with reference to Figs.
• the structure had a layer thickness of about 2.1 to 2.2 microns.
• the residual layer remaining in the recess after stamping had a thickness of about 150 nm.
• the layer thicknesses are shown in the region of the resulting structure 10 and in the recess 11. After the treatment with direct plasma described above and a linear electrode which is driven over the substrate, the layer thicknesses shown in FIG. 6 (b) result.

Applications Claiming Priority (4)

Publications (2)

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Citations (9)

• 2005
  • 2005-09-22 DE DE102005045331A patent/DE102005045331A1/de not_active Ceased
• 2006
  • 2006-06-16 WO PCT/EP2006/005801 patent/WO2006133956A2/de active Application Filing

Patent Citations (9)

Non-Patent Citations (2)

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