THREE-DIMENSIONAL MICRO DEVICES AND METHOD FOR THEIR PRODUCTION

Abstract

Three-dimensional micro devices usable as electromagnetic and magnetomechanical energy converters, as micromagnetic motors or generators, and methods for their production. The three-dimensional micro devices exhibit high efficiency even at dimensions on the microscale and below, and the method for production, as well as mass production, is simple and economical. Moreover, the three-dimensional micro devices at least include one three-dimensional device produced using roll-up technology. This three-dimensional device includes all functional and structural components for full functionality. At least one functional or structural component is an element that is at least partially freely movable at least partially within a surrounding element and is arranged such that it can be rotated at least around one of its axes.

Claims

1. Three-dimensional micro devices, at least composed of one three-dimensional device produced using roll-up technology, which device comprises all functional and structural components for full functionality, wherein at least one functional or structural component is an element that is at least partially freely movable, at least partially within a surrounding element and is arranged such that it can be rotated at least around one of its axes.

2. The three-dimensional micro devices according to claim 1 in which the functional and structural components are present for motors, generators, sensors, in particular magnetic sensors that utilize the effects of MR, GMR, TMR and/or Hall effects, spin effects or induction: for pumps, diodes, capacitors, resistors, piezo devices; optical devices such as lenses, waveguides, gratings; and/or turbines, transistors and/or actuators, in prosthetic devices, and/or in microfluidics.

3. The three-dimensional micro devices according to claim 1 in Which rotors, stators, windings, electrical and/or electronic elements, electrical contacts are present as functional components.

4. The three-dimensional micro devices according to claim 1 in which the functional and/or structural components are composed entirely or partially of metallic materials such as copper, gold and/or magnetic materials and/or semiconductor materials and/or polymer materials and/or insulator materials.

5. The three-dimensional micro devices according to claim 4 in which a ferromagnetic or ferrimagnetic or paramagnetic material that is Co, Fe, Nd, Ni, or Co-, Fe-, Nd- or Ni-based alloys, or is made of alloys of these materials, is present as magnetic material.

6. The three-dimensional micro devices according to claim 1 in which the devices are structurally composed of a planar multilayer system.

7. The three-dimensional micro devices according to claim 1 in which, for a motor or generator or sensor or actuator, at least one rotor is present such that it is freely movable in a stator, and furthermore all other functional and structural components for full functionality as a motor or generator are present.

8. The three-dimensional micro devices according to claim 1 in which the devices are positioned in a fixed mariner on a substrate, advantageously on the substrate on which they were produced.

9. The three-dimensional micro devices according to claim 1 in which the devices have at least one outer dimension that is less than or equal to 0.5 mm, advantageously less than or equal to 0.1 mm, more advantageously on the sub-micrometer scale less than or equal to 200 m, advantageously less than or equal to 1 m.

10. A method for the production of micro devices in which. at least one three-dimensional micro device is produced on a substrate using roll-up technology, wherein the at least one three-dimensional micro device is completely produced with all functional and structural components within the overall process and is fully functional following production, and wherein for the three-dimensional micro device, at least one element that is at least partially freely movable partially within a surrounding element is produced using roll-up technology, with the at least one element being produced such that it can be rotated at least around one of its axes.

11. The method according to claim 10 in which a plurality of identical and/or different three-dimensional micro devices is produced simultaneously on a substrate.

12. The method according to claim 10 in which, for the individual three-dimensional micro devices, at least one sacrificial layer is applied on a substrate and multiple identically or differently composed and structured layer systems are applied thereon, and the individually applied layer systems are rolled up into multilayer systems by the partial or complete removal of the sacrificial layer or sacrificial layers.

13. The method according to claim 10 in which, for the production of a motor or generator or sensor or actuator, a layer system is applied on a substrate with at least one sacrificial layer, in which layer system the layers for the at least partially surrounded functional and structural components are rolled up first and the layers for the at least partially surrounding functional and structural components are then rolled up.

14. The method according to claim 10 in which, for the production of fully freely movable elements at least partially within a surrounding element, at least one additional sacrificial layer is applied, and the layer system for the freely movable element applied thereon, after the layer system for the production of the surrounding element.

15. The method according to claim 14 in which at least one layer is applied in a strained manner in place of a sacrificial layer or under or on top of a sacrificial layer, wherein for a layer stack a strain gradient is created across the height of the layer stack, and the strain is released in order to roll up the layer stacks, or the at least one layer is strained for the rolling-up.

16. The method according to claim 15 in which a hydrogel or a polymer layer is applied as a layer.

Description

[0067] The invention is explained in greater detail below with the aid of multiple exemplary embodiments.

[0068] Wherein:

[0069] FIG. 1 shows the layout for the layers of a stator according to the invention for a motor with (a) a hydrogel layer of the stator, (b) a polyimide layer of the stator, (c) a hydrogel layer of the rotor, (d) a polyimide layer of the rotor, (e) a layer stack, as viewed from the substrate side; the sacrificial layers are not illustrated;

[0070] FIG. 2 shows a basic illustration of the method sequence for the production according to the invention of a micro motor as a three-dimensional micro device according to the invention, with [0071] (a) the illustration of the initial structure of the layer stack, [0072] (b) the illustration of the rolled-up rotor on the stator layers, [0073] (c) the illustration of the rolling-up of the stator layer (50% complete), [0074] (d) the illustration of the rolled-up stator, [0075] (e) the view of the cross section of the micro motor with a rotor and stator that were produced using roll-up technology.

EXAMPLE 1

[0076] A substrate of silicon dioxide with the dimensions of 100100 mm.sup.2 and a thickness of 1 mm is repeatedly rinsed in a dishwasher with surfactants (anionic and ionic) and DI water for 1 h 30 min.

[0077] On the substrate surface, a monolayer of 3-(trimethoxysilyl)propyl methacrylate (Polysciences Europe GmbH) is applied as an adhesive layer over the entire surface, in that the substrates are left for a total of 3 h under vacuum at 150 C. with the vapor from the silane molecules and water.

[0078] i) On this adhesive layer, a layer of acrylic acid (AA) (Alfa Aesar) and hydrated La.sup.3+ (Alfa Aesar) is applied as a sacrificial layer over the entire surface. For this purpose, a mixture of 30 g AA and 15 g LaCl.sub.3 in water is produced, which mixture results in a precipitate of LaAA at an increased solution pH of 10. This precipitate is collected through filter paper in a desiccator, where this precipitate is dried for 10 h at 40 C. Next, the material obtained is dissolved in AA and, at a concentration of 25 wt %, photosensitized with 2 wt % 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone and 3 wt % methyldiethanolamine (Sigma-Aldrich Co. LLC, Germany). From this sacrificial layer solution, a 200-nm thick layer is produced by means of spin coating at 3500 rpm for 35 s. Drying is carried out at 60 C. for 5 min, and the structuring then occurs by means of a treatment with a 405-nm mercury h-line (20 mW/cm.sup.2) for 3 min through a glass/Cr mask with the use of a SUSS MA45 (Karl Suss KGGmbH & Co., Munich-Garching, Germany) mask aligner. Development takes place in DI water for 15 s with a subsequent rinsing in 1-methoxy-2-propyl acetate (Sigma-Aldrich Co. LLC, Germany). Finally, the samples are annealed at 220 C. for 5 min under a nitrogen atmosphere in order to remove all residual solvent and to stabilize the layer.

[0079] ii) On the adhesive layer, a polymeric swelling layer is applied in a shape according to FIG. 1 (a), which layer is produced from a reaction of N-(2-hydroxyethyl)acrylamide (HEAA) and poly(ethylene-alt-maleic anhydride) (PEMA) in N,N-dimethylacetamide (DMAc), wherein a 2 wt % 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone (Sigma-Aldrich Co. LLC, Germany) is dissolved in DMAc. 6 g PEMA is dissolved in 50 ml DMAc and 5.8 g HEAA is added. The reaction takes place for 10 h at room temperature. Using spin-coating, this solution is applied to the sacrificial layer at 4000-8000 rpm. The thickness of the resulting swelling layer is 1000-300 nm. After the polymeric swelling layer is dried at 60 C. for 5 min, the layer stack is exposed on the substrate for 1.5 min to a 405-nm mercury h-line (20 mW/cm.sup.2) through a glass/Cr mask with the use of a SUSS MA45 (Karl Suss KGGmbH & Co., Munich-Garching, Germany) mask aligner. With the mask, the exposure in the swelling layer takes place in the shape according to FIG. 1 (a). Development of the mixture is carried out in one part by volume DMAc and 2 parts by volume propylene carbonate (Sigma-Aldrich Co. LLC, Germany) for 30 s with a subsequent rinsing in isopropyl alcohol. Finally, the layer stack is annealed on the substrate at 200 C. for 5 min under a nitrogen atmosphere in order to remove excess solvents.

[0080] The differential strain is achieved in the swelling layer (hydrogel) by swelling in an aqueous medium. The swelling of the swelling layer is carried out after the entire layer stack has been applied. During the swelling, the sacrificial layer is thus completely removed, and the rolled-up layer stack is therefore detached from the substrate. The state of the adhesive layer remains unchanged.

[0081] iii) As a stator layer, a polyimide layer is applied on the swelling layer (FIG. 1 (b)). The photosensitive polyimide is produced by the reaction of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BPDA) and 3,3-diaminodiphenyl sulfone (DADPS) in N,N-dimethylacetamide (DMAc), photosensitized with (dimethylamino)ethyl methacrylate (DMAEMA) and with 2 wt % 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone (Sigma-Aldrich Co. LLC, Germany). The polyimide synthesis was carried out by dissolving 9.93 g DADPS in 20 ml DMAc with a subsequent addition of 12.8 g BPDA. After the mixture was stirred for 12 h at 70 C., the solution of polyamide acid (PAA) in DMAc was achieved. The solution of PAA is neutralized by a reaction with 12.5 g DMAEMA. Using spin coating, the polyimide was applied to the swelling layer in a rectangular shape across the entire surface as a second carrier layer at 2000-8000 rpm for 35 s. A polyimide layer with a thickness of 1700-500 nm is created. After the drying of the polyimide layer, exposure occurs through a glass/Cr mask in the shape according to FIG. 1 (b), wherein at 60 C. for 5 min, the sample is exposed for 1.5 min to a 405-nm mercury h-line (20 mW/cm.sup.2) with the use of a SUSS MA45 (Karl Suss KGGmbH & Co., Munich-Garching, Germany) mask aligner for structuring. Development takes place in a mixture of one part by volume 1-ethyl-2-pyrrolidone, 0.58 parts by volume methyl alcohol and 0.5 parts by volume diethylene glycol monoethyl ether for 1 min with a subsequent rinsing in propylene glycol monomethyl ether acetate (Sigma-Aldrich Co. LLC, Germany).

[0082] The imidization of the polyimide layer is carried out by simultaneously removing the excess solvents on a hot plate at 220 C. for 5 min under a nitrogen atmosphere.

[0083] On the layer stack that forms the stator after the rolling-up, the layer stack for the rotor is then applied.

[0084] For this purpose, a layer of acrylic acid (AA) (Alfa Aesar) and hydrated La.sup.3+ (Alfa Aesar) is first applied as a sacrificial layer for the rotor layer stack (FIG. 2 (a)) over the entire surface in the same sequence. The composition and production take place according to the specifications in i). A polymeric swelling layer is then applied according to the composition and production specified in ii) for the layer stack of the rotor. The application of the polyimide layer then also occurs according to iii) and FIG. 1 (e) as a rotor layer.

[0085] Then, by means of a selective etching of the sacrificial layer and a swelling of the swelling layer in a solution of 0.5 M sodium diethylenetriaminepentaacetate (DTPA) (Alfa Aesar, UK), the previously planar 2D layout of the layer stack for the rotor is first rolled up (FIG. 2 (b)).

[0086] Through an additional selective etching of the sacrificial layer and swelling of the swelling layer in a solution of 0.5 M sodium diethylenetriaminepentaacetate (DTPA) (Alfa Aesar, UK), the previously planar 2D layout of the stator is then rolled up into a 3D Swiss roll (self-assembly).

[0087] After the etching process, the structures are washed in DI water and then placed in a solution of DI water and isopropyl alcohol at a ratio of 1:5 for 10 min and finally dried under ambient conditions.

[0088] During and/or after the application of the layer stacks for the micro motor, for the production of a sensor composed of Ta(2 nm)/[Co(0.6 nm)/Pt(1 nm)]5/Cu(1.8 nm)/[Co(0.6 nm)/Pt(1 nm)]5/Co(0.6 nm)/IrMn(5 nm)/Ta(2 nm) a structured layer stack is applied to the polyimide layer next to the layer stack for the micro motor using magnetron sputter deposition in a high-vacuum chamber (base pressure: 410.sup.7 mbar; Ar sputter pressure: 610.sup.4 bar; deposition rate 0.2 /s) in the presence of a homogeneous magnetic field of 40 mT for the creation of the magnetic anisotropy. Together with the layer stack for the micro motor, or afterwards, the layer stack for the sensor is rolled up and can then be transported together with the micro motor onto a different substrate, where it can be functionally positioned.

[0089] With the three-dimensional micro motor produced in such a manner, it is for example possible to power pumps for blood or other micro fluids or perform surgery movements on the micrometer scale.

[0090] The individual micro device has a small footprint and, compared to a similar device according to the prior art, operates more efficiently, can be more easily produced, and production is more cost-efficient.

EXAMPLE 2

[0091] With micro motors produced according to Example 1, 35 motors can be produced simultaneously on a substrate in a single production process over the entire 100100 mm.sup.2 substrate. For this purpose, the individual layers can each be structured and produced separately one after another with the respective masks, or using one mask with all 35 shapes.

[0092] In the case of separate structuring, different shapes and sizes of the micro motors can also be produced on the substrate.

[0093] Provided that the micro motors produced are completely detached from the substrate, additional micro devices according to the invention can be produced on the same substrate.