DE19747813A1 - Element used in manufacture of electronic components - Google Patents

Abstract

Block copolymer films are applied to a surface of a substrate so that metal or metal oxide films can be deposited. The element comprises a substrate, a film comprising a polymer containing different blocks forming a microdomain structure by segregating the blocks on the substrate surface, and metal and/or metal chalcogenide layers whose local layer thickness varies depending on the microdomain structure. An Independent claim is also included for the production of the element which involves applying the polymer containing the blocks onto the substrate, and coating the substrate with the metal and/or metal chalcogenide layers.

Description

The present invention relates to an element which consists of a substrate, a film on top of it, which contains a different block Polymer that forms a microdomain structure on the substrate surface, comprises, and a film of metal and / or metal chalcos arranged thereon is constructed, a process for the surface structuring of Substrates as well as surface-structured substrates in the nanometer range. The The present invention is based in particular on the self-organization thinner Two-block copolymer films in which the formation is chemically different Surface domains the locally selective deposition of a metallic or metal chalcogenide film allows.

Periodic and aperiodic microstructures from a few micrometers to some 100 nanometers are used for a variety of applications, in particular for electronic and optical components, sensors and in the micro technology manufactured using lithographic techniques. Another reduction The geometrical dimensions not only enable another mini-tari sation, but also allows the use of dimension-dependent physical Properties such as B. quantum effects, superferromagnetic properties or electron plasmon resonances. Basically requires implementation in macroscopic effects or measurands but a high uniformity of a Ensembles of microscopic structures.

For structures of interest below 100 in this context nm the application of conventional lithographic processes is extreme difficult and not very economical. Complementary to conventional processes  new methods have to be developed for this, which are either based on a size-controlled growth of inorganic structures or on moleku laren concepts of organic and macromolecular chemistry are based.

A two- or multiblock copolymer consists of chemically different ones macromolecular chains, which are at the ends or at another molecular position (for example in the case of star or graft block copolymers) are covalently linked. In most cases, the different mix blocks and do not separate in so-called microdomains. Their size and morphological order is determined by the Volu proportions of the individual blocks and the molecular weight distribution determined. For example, changing the volume fraction of the polymer blocks allows adjustment different microdomain structures such. B. balls, cylinders and lamella len. The periods that can thus be achieved are typically between 10 and 200 nm.

Microphase separation can also be observed in ultra-thin films the. The decisive factor here is the extent to which the microdomain structure and its Organization of interface and surface energies and geome trical narrowing is affected.

Park et al. describe the transfer of the microdomain structure of a two lock copolymers on an underlying silicon nitride substrate (Park et al., Science 1997, 276, 1401 and Appl. Phys. Lett. 1996, 68, 2586). Two different techniques based on reactive ion etching allow the manufacture Positioning holes with a diameter of 20 nm with a periodicity of 40 nm as well as the corresponding inverse structure. In the same way, could hanging channels of 30 nm diameter and 15 nm distance on a substrate be transmitted. Microdomain regions were made from polybutadiene of a polystyrene-b-polybutadiene two-block copolymer with ozone gas and triggered from the polystyrene matrix or marked with osmium atoms. Both Methods result in a local inhomogeneity with respect to the etching reticule what ultimately enables two-block copolymer patterns as a mask for  to use nanometer-sized surface structures. Such patterns in the area In principle, a few nanometers can be used for the production of nanostructures and to become technologically usable for use as masks for lithography.

Until now, optical lithography processes were used for structuring over 100 nm very successful. Since this is a parallel process, which also a allows high throughput, it clearly dominates the microelectronic production circuits. The minimum structure size that can be achieved is by a technical compromise between the physically possible resolution and the required depth of field determined by apparatus. They are in production Dimensions of integrated circuits are already below 350 nm as standard Achieved use of X-ray light with very high technical effort Dimensions of approximately 90 nm.

With electron beam and ion beam lithography one can longer structures with nanometer dimensions, and corresponding Plants are commercially available. Atomic beam lithography allows through the Control of the interaction of the atomic rays with light masks, large area periodic line patterns and various two-dimensional periodic structure to generate structures with a resolution below 100 nm. Thereby atoms either deposited directly on a substrate or for the modification of organic ones Resists used.

By utilizing crystal growth on GaAs (311) B-oriented sub not only small units but also well-ordered Quan could strate tendot structures are shown. After the growth of a thin InGaAs The strained InGaAs film breaks in a layer over an AlGaAs buffer layer small pieces that are buried spontaneously under AlGaAs. This is how they are formed naturally ordered rows of AlGaAs microcrystals with one Disc-shaped InGaAs dots. Leave the size and spacing of the dots independently of each other solely through the growth parameters troll. The photoluminescence spectra of the dots are of high efficiency and narrow line widths marked.  

However, it is disadvantageous for the methods described in the prior art that they are not economically viable and / or there are no periodic structures in the deliver lower nanometer range and / or only by physical parameters can be controlled and are therefore too expensive in terms of equipment.

The present invention is therefore based on the object of a molecule Ren concepts based on organic or macromolecular chemistry Process that describes the surface structuring of substrates in the nanometer allowed range, as well as in the lower nanometer range (preferably less than 20 nm, more preferably less than 5 nm) surface-structured substrates to deliver.

This object is achieved by the embodiment characterized in the claims forms solved. In particular, an element is provided comprising a Substrate and a film applied to at least one side of the substrate, which comprises at least one polymer containing different blocks, which has a microdomain structure on the substrate surface by Segrega tion of the different blocks forms such that at least a part of the Blocks are essentially parallel to the substrate surface and at least one other part of the blocks are essentially perpendicular to the substrate surface arranges, and arranged on the film one or more, the same or under different metal and / or metal chalcogenide layers, their local layer thickness varies depending on the microdomain structure of the polymer.

The polymer used according to the invention is preferably made of block copolyme ren, star polymers, graft copolymers and micro arm star polymers elects.

The polymer is more preferably polystyrene-b-polyethylene oxide, polystyrene-b- poly (2-vinylpyridine), polystyrene-b-poly (4-vinylpyridine) or a mixture thereof. The polystyrene block in it can also be replaced by other non-polar polymers, such as polyisoprene, polybutadiene, polymethyl methacrylate or other polymethacrylates are replaced. The second or polar block in one  such a two-block copolymer can be one which is also one if possible strong interaction with the substrate. Examples include poly acrylic acid, polymethacrylic acid, amino-substituted polystyrenes, polyacrylates or polymethacrylates, amino-substituted polydienes, polyethyleneimines, saponified Polyoxazolines or hydrogenated polyacrylonitrile. The first block can also be made be built up a polar polymer, but with the proviso that then Substrate is chosen so that it mainly, i. H. selective, with the second polar block interacts. The metal compound to be used and the corresponding polymer blocks are to be chosen such that the metal compound preferably interacts with one of the polymer blocks or interacts with one of the Adds polymer blocks.

The metal and / or metal chalcogenide layer is preferably selected from Cr, Cr _x O _y , Ti, TiO ₂ , In, In _x O _y , Si, SiO ₂ , Au, Ag, Ag _x O _y , Pt, and Pd. The metal oxides are preferably used as metal chalcogenides.

Usable substrates are precious metals, oxidic glasses, mono- or multicrystalline substrates, semiconductors, metals with or without a passivated surface, insulators or generally substrates with high resistance to the subsequent etching procedures. In particular, these are Pt, Au, GaAs, In _y GaAs, Al _x GaAs, Si, SiO ₂ , Ge, Si _x N _y , Si _x GaAs, InP, InPSi, GaInAsP, glass, graphite, diamond, mica, SrTiO ₃ and its doped modifications.

The present invention further provides a method for producing the element, which comprises the following steps:

• (a) applying at least one poly containing different blocks mer on a substrate, the polymer on the substrate surface Micro-domain structure through segregation of the different blocks forms such that at least a part of the blocks essentially parallel to the substrate surface and at least some other part of the blocks is arranged substantially perpendicular to the substrate surface, and
• (b) coating the substrate obtained in step (a) with one or more ren, the same or different metal and / or metal chalcogenide  layers whose local layer thickness depends on the microdom The structure of the polymer varies.

In step (a) of the method according to the invention, the application of the film preferred in monolayers or multilayers on at least one side of a substrate identify by immersion, pouring, spin spinning or by adsorption diluted solution performed. Application in mono- or multi-layers by dipping from a dilute solution.

Typically, an amphiphilic two- or three-block copolymer, star polymer, graft copolymer or micro-arm polymer is on a substrate, such as. B. mica, adsorbed from a low-concentration chloroform solution (preferably between 10 ^-6 and 100 mg / ml), or by rotary centrifugation (1-10 ⁵ U / min) or by pulling a substrate out of the solution at a defined speed between, for example 0.001 mm / min and 2 m / min applied.

The thickness of the film formed and the interaction of the substrate with the different components or blocks of the polymer system used is chosen such that a microdomain structure is formed on the substrate surface by segregation of the different blocks in such a way that at least some of the blocks form in the essentially parallel to the substrate surface and at least one other part of the blocks arranged essentially perpendicular to the substrate surface, ie the substrate surface is "wetted" by one or more blocks ("arranged essentially parallel"), whereas the other blocks, however, the substrate surface " retrofit "(" arranged essentially vertically "). In Fig. 1, such segregation of different blocks with respect to a deposited polymer film is shown schematically. The free surface of the polymer film preferably has chemically different domains in a size range of, for example, 5 to 500 nm. Depending on the polymer system used (z. B. Polysty rol-b-polyvinylpyridine) and the block ratios accordingly form by self-organization. B. quasi-hexagonal arranged islands or webs with a diameter of 5 to 500 nm, for example. These islands or webs are aggregates of the blocks dewetting the surface. The island or web volume (125 nm ³ - 1 µm ³ ) and the lateral spacing of the aggregates is set by the molecular weights of the blocks of the polymer system used and by the extent of the interaction with the substrate. The distance between the aggregates can vary, for example, between 5 nm and 1 μm. This results in regular microdomain formation on the surface of the substrate, the surface domains differing chemically and / or physically (see FIG. 1).

In a preferred embodiment, the film can be subjected to an electrical field (1-10 ⁶ V / cm) during or after the application in order to anisotropically align the microdomain structure formed, in particular the webs formed, or to change its size ranges, so that a targeted Anisotropic alignment of the webs or islands takes place over macroscopic areas. For the anisotropic alignment of the microdomain structure formed, the electric field can preferably be applied at elevated temperature. Alignment in an electrical field (1-10 ⁶ V / cm) during adsorption can be done in solution or in a solvent flow. With 1 g of polymer z. B. coated up to 2000 m ² .

In step (b), the corresponding metal and / or metal chalcogenide layers, for example, by vapor deposition, sputtering, chemical vapor deposi tion (CVD), Molecular Chemical Vapor Deposition (MOCVD) or Chemical Beam Epitaxy (CBE) or by deposition from solution on a defined substrate temperature between 50 and 1500 Kelvin applied. This results in a Metal / metal chalcogenide layer or film with locally varying layer thickness corresponding to the lateral upper specified by the block copolymer surface structure of the polymer film (island and web diameter, for example 5-500 nm and periodicity, for example 5 nm-1 µm), the poly any given topography difference is increased drastically. More typical the height differences are due to the locally selective separation formation of the corresponding metal and / or metal chalcogenide layers between  1 and 100 nm. The metal / metal chalcogenide layers structured in this way the substrate surface of the element, its thickness over distances of 5 nm and 1 µm can vary, for example, between 1 and 100 nm, can fiction as masks for the location-selective structuring of different sub strate can be used. The masks cannot only be used directly on the desired substrate are generated, but also by a swim technology can be transferred from one substrate to another.

Another object of the present application is a method for Production of surface-structured substrates, in which the Invention corresponding element of a reactive ion etching method, an ion sputtering method or subjected to a wet chemical method or a combination thereof is, wherein at least a part of the metal and / or metal chalcogenide layer together with the one essentially parallel to the substrate surface Blocks containing polymer film and at least part of the metal and / or Metallchalkogenidschicht without or together with the substantially lower polymer film containing blocks to the substrate surface due to and depending on the locally selectively deposited metal and / or metal chalcogenide layer and the duration of the respective method or Combination of it is removed. Partial removal of the metal and / or Metal chalcogenide layer together with the polymer film generally results to reinforce the through the polymer / metal and / or metal chalcogenide layer given structure or topography. In a preferred out the metal and / or metal chalcogenide layer together with completely removed from the polymer film, whereby the polymer / metal and / or metal chalcogenide layer given structure or topography in a relief structure of the underlying substrate is transferred. Preferably the element is subjected to an argon ion sputtering process. In a In another embodiment, the element can first be an oxygen plasma and then subjected to an argon ion sputtering process. It can but also an argon / oxygen ion mixture can be used for sputtering. The sputtering procedure can be repeated any number of times.  

Due to the property of the locally selectively deposited metal and / or Metal chalcogenide layer as a mask is achieved through the reactive ion etching process or ion bombardment or a wet chemical process the site-selective Ab wearing underlying substrates or the reinforcement of the poly mer / metal or metal chalcogenide layers given structure or Topography, whereby regularly arranged structures, especially islands, Columns and bars, depending on the given polymer / metal or Metal chalcogenide structures can be generated.

The method presented thus allows the etching of bars, columns and Islands and their inverse structures with lateral dimensions between for example, 5 and 500 nm over large macroscopic areas substrates. The height and depth dimensions of the Structures can exceed the lateral dimensions many times over.

The structured polymer / metal and / or metal that can be used as masks Chalcogenide films can not only directly on the desired substrate be generated, but also by a swimming technique from a sub strat be transferred to another. The metal and / or metal chalcogenide layer either together with at least part of the polymer films or without the polymer film before the reactive ion etching process, ions sputter process or wet chemical process on another substrate transferred. The transfer is preferably carried out by floating or floating men performed on liquid media, preferably water.

The surface-structured substrates which can be produced by the process according to the invention are preferably made of noble metals, oxidic glasses, mono- or multicrystalline substrates, semiconductors, metals with or without a passivated surface or insulators. They are more preferably made of Pt, Au, GaAs, In _y GaAs, Al _x GaAs, Si, SiO ₂ , Ge, Si _x N _y , Si _x GaAs, InP, InPSi, GaInAsP, glass, graphite, diamond, mica, SrTiO ₃ or their doped modifications selected.

The figures show:  

Fig. 1 shows the schematic representation with respect to the lateral phase separation of a Block Ab-Block B two-block copolymer.

FIG. 2 shows the schematic illustration with regard to the selective deposition of, for example, titanium over, for example, polystyrene domains.

FIG. 3 shows atomic force micrographs showing thin polymer films on mica consisting of poly [styrene] _x -b-poly [2-vinylpyridine] _y -Zweiblockcopolyme ren (x and y indicate the number of monomer units per each block of: (a) Poly [ styrene] ₁₅₀ -b-poly [4-vinylpyridine] ₁₁₀ , (b) poly [styrene) ₃₀₀ -b-poly [2-vinylpyridine] ₃₀₀ , (c) poly [styrene] ₅₅₀ -b-poly [2-vinylpyridine] ₆₆₀ , (d) poly [styrene] ₅₅₀ -b-poly [2-vinylpyridine] ₁₄₀₀ , (e) poly [styrene] ₈₀₀ -b-poly [2-vinylpyridine] ₈₆₀ , (f) poly [styrene] ₁₃₅₀ - b-poly [2-vinylpyridine] ₄₀₀ , (g) poly [styrene) ₁₇₀₀ -b-poly [2-vinylpyridine] ₄₅₀ , (h) poly [styrene] ₃₃₀ -b-poly [4-vinylpyridine] ₁₃₀ .

Fig. 4 shows atomic force micrographs and the height profiles along a line horizontally running across the surface of the polymer film (f) coated with Ti-be in Example 1.

Fig. 5 atomic force micrographs of the Ti / TiO ₂ (3 nm) coated polymer film (f) after treatment with argon ions produced in Example 1 shows (1.1 keV / 0.3 mA / cm ²⁾ for 15 min and the height profile along a line running horizontally across the surface.

Fig. 6 (a) shows the topography, and (b) the relative imaging of the friction coefficient of a prepared in Example 1, the inventive surface-structured substrate on the basis of the used polymer film (f), which was subjected to argon ion treatment. Ti layers are only found on the islands.

FIG. 7 shows a force micrograph of an adsorbed, laterally phase-separated poly [styrene] ₈₀₀ -poly [2-vinylpyridine] ₄₃₀ -b-poly [methyl methacrylate] ₇₃₀ three-block copolymer on mica.

The present invention is illustrated below by examples.

example 1

Thin polymer films consisting of (a) poly [styrene] ₁₅₀ -b-poly [4-vinylpyridine] ₁₁₀ -, (b) poly [styrene] ₃₀₀ -b-poly [2-vinylpyridine] ₃₀₀ -, (c) poly [ styrene] ₅₅₀ -b-poly [2-vinylpyridine] ₆₆₀ -, (d) poly [styrene] ₅₅₀ -b-poly [2-vinylpyridine] ₁₄₀₀ -, (e) poly [styrene] ₈₀₀ -b-poly [2 - vinylpyridine] ₈₆₀ -, (f) poly [styrene] ₁₃₅₀ -b-poly [2-vinylpyridine] ₄₀₀ -, (g) poly [styrene] ₁₇₀₀ -b- poly [2-vinylpyridine] ₄₅₀ -, (h) poly [Styrene] ₃₃₀ -b-poly [4-vinylpyridine] ₁₃₀ two-block copolymers were applied to mica surfaces by pulling the mica platelets at a rate of 5 mm / min from a 0.01 mg / ml concentrated chloroform polymer solution . Fig. 3 shows atomic force micrographs of the dry films. Table 1 below shows the specific structural parameters of films (a) to (h).

Table 1: Surface structure parameters of various two-block copolymers

The polymer films (a) to (h) were then vapor-deposited with differently thick Ti layers. The layer thicknesses to be expected theoretically on a chemically homogeneous or smooth substrate were determined by means of quartz crystal technology. Depending on the thickness of the vapor-deposited layers, the aggregate heights were characterized by atomic force microscopy and measured by atomic force microscopy (see FIG. 4). Table 2 below shows the respective aggregate heights with respect to the polymer film (f) (poly [styrene] ₁₃₅₀ -b-poly [2-vinylpyridine] ₄₀₀ ) with increasing Ti layer thickness.

Table 2: Aggregate height of the polymer film (f) (poly [styrene] ₁₃₅₀ -b-poly [2-vinylpyridine] ₄₀₀ ) with increasing Ti layer thickness in comparison to the value to be expected according to the quartz crystal technique

The Ti / polymer films are then treated for 10 min in an oxygen plasma to form a thin TiO ₂ skin and then treated with argon ions (1.1 keV / 0.3 mA / cm ² ) for 15 min. The island height increases from 11 to 27 nm (see Fig. 5). After the argon treatment, the friction force microscopy shows a material contrast between the islands and the surface lying between the islands (cf. FIG. 6). It was found that TiO _{2 covered} the islands and that the mica substrate between the islands was removed to a minimum depth of 16 nm.

Example 2

Adsorbed polystyrene-b-poly (2-vinylypyridine) -b-polymethyl methacrylate three-block copolymer films are deposited on mica by pulling a mica surface from a 0.01 mg / ml solution at a rate of 5 mm / min. Fig. 7 shows an AFM image of the surface topology. Regularly arranged polystyrene islands are surrounded by a ring made of polymethyl methacrylate.

Claims (23)

1. Element, comprehensive
a substrate,
a film applied to at least one side of the substrate, which comprises at least one polymer containing at least different blocks, which forms a microdomain structure on the substrate surface by segregation of the different blocks in such a way that at least some of the blocks are substantially parallel to the substrate surface and at least another part of the blocks is arranged substantially perpendicular to the substrate surface, and
arranged on the film one or more, identical or different metal and / or metal chalcogenide layers, the local layer thickness of which varies depending on the microdomain structure of the polymer. 2. The element of claim 1, wherein the different blocks containing Polymer from block copolymers, star polymers, graft copolymers and Microamster polymer is selected. 3. Element according to claim 2, wherein the polymer of polystyrene-b-poly (2- vinylpyridine), polystyrene-b-poly (4-vinylpyridine), polystyrene-b-poly (2-vinylpy ridin) -b-polymethyl methacrylate or mixtures thereof is selected. 4. Element according to any one of the preceding claims 1 to 3, wherein the metal and / or metal chalcogenide layer made of Cr, Cr _x O _y , Ti, TiO ₂ , In, In _x O _y , Si, SiO ₂ , Au, Ag, Ag _x O _y , Pt, and Pd is selected. 5. Element according to one of the preceding claims 1 to 4, wherein the substrate made of Pt, Au, GaAs, In _y GaAs, Al _x GaAs, Si, SiO ₂ , Si _x GaAs, Ge, Si _x N _y , InP, InPSi, GaInAsP, glass, graphite, diamond, mica, SrTiO ₃ or their doped modifications is selected. 6. Element according to any one of the preceding claims, wherein the free Surface of the polymer film chemically different domains in one Size range from 5 to 500 nm. 7. A method of manufacturing the element according to any one of the preceding claims 1 to 6, comprising the steps of

• (a) applying at least one polymer containing different blocks to a substrate, the polymer on the substrate surface forming a microdomain structure by segregation of the different blocks in such a way that at least some of the blocks are substantially parallel to the substrate surface and at least one other part the blocks are arranged substantially perpendicular to the substrate surface, and
• (b) coating the substrate obtained in step (a) with one or more, identical or different metal and / or metal chalcogenide layers, the local layer thickness of which varies depending on the microdomain structure of the polymer.

8. The method of claim 7, wherein in step (a) the application of the Polymer films by immersion, casting, spin spinning or by Adsorption is carried out from dilute solution. 9. The method of claim 8, wherein the application is by dipping is carried out from dilute solution. 10. The method of claim 9, wherein during the application of the film electric field is applied to the formed microdomain structure align anisotropically or change their size ranges. 11. The method of claim 10, wherein after application of the film  electric field is applied to the formed microdomain structure align anisotropically or change their size ranges. 12. The method of claim 10 or 11, wherein for anisotropic alignment the formed microdomain structure the electric field at increased Temperature is applied. 13. The method according to any one of claims 7 to 12, wherein the metal and / or Metal chalcogenide layers by vapor deposition, sputtering, chemical vapor Deposition (CVD), Molecular Chemical Vapor Deposition (MOCVD) or Chemical Beam Epitaxy (CBE) or by deposition from solution a defined substrate temperature between 50 and 1500 Kelvin to be led. 14. A method for producing surface-structured substrates, wherein the element according to one or more of claims 1 to 6 one reactive ion etching method, an ion sputtering method or a wet one chemical method or a combination thereof, wherein at least part of the metal and / or metal chalcogenide layer along with that essentially parallel to the substrate surface polymer blocks containing pointing blocks and at least part of the Metal and / or metal chalcogenide layer without or together with the blocks essentially perpendicular to the substrate surface containing polymer film due to and depending on the location selectively deposited metal and / or metal chalcogenide layer as well the duration of the reactive ion etching method and / or the ion sputtering Method and / or the wet chemical method is removed. 15. The method according to claim 14, wherein the metal and / or metal chalcogen layer is completely removed together with the polymer film, wherein the of the polymer / metal and / or metal chalcogenide layer predefined structure in a relief structure of the underlying substrate is transferred.   16. The method of claim 14 or 15, wherein the element is an argonio NEN sputtering is subjected. 17. The method of claim 16, wherein the element is first an oxygen plasma and then subjected to an argon ion sputtering process becomes. 18. The method according to any one of claims 14 to 17, wherein before the reactive Ion etching process, ion sputtering process or wet chemical process Ren the metal and / or metal chalcogenide layer together with minde least part of the polymer film or without the polymer film on other substrate is transferred. 19. The method of claim 18, wherein the transfer is by floatation liquid media is carried out. 20. The method of claim 19, wherein the liquid medium is water. 21. Surface-structured substrate, producible by a process according to one of claims 14 to 20. 22. The substrate of claim 21, which is made of precious metals, oxidic Glä sern, mono- or multicrystalline substrates, semiconductors, metals with or is selected without a passivated surface or insulators. 23. The substrate of claim 22, which is made of Pt, Au, GaAs, In _y GaAs, Al _x GaAs, Si, SiO ₂ , Ge, Si _x N _y , Si _x GaAs, InP, InPSi, GaInAsP, glass, graphite, diamond , Mica, SrTiO ₃ or their doped modifications is selected.