Ultra compact micro capacitor and method for producing same

Abstract

The present invention relates to the area of micro- and nanoelectronics and relates to ultra-compact micro capacitors, how they can be used, for example, in electrical and electronic devices. The object of the present invention consists in specifying an ultra-compact micro capacitor with the highest capacity. The problem is solved by an ultra-compact micro capacitor which is made from a rolled-up layer stack of alternatingly arranged layers of dielectric and/or electrically insulating and electrically conductive materials with rolled-up lengths of the layer stack of at least 1 mm, and an absolute electrical storage capacity of at least 10 nF. The problem is additionally solved by a method, in which a layer containing a water-soluble cellulose derivative is applied to a substrate and a layer stack to same, the layer containing the cellulose derivative is removed from the substrate using water, an organic solvent and/or an organic solvent mixture, and the layer stack is rolled up with a rolling speed of more than 0.1 mm/min.

Claims

1. An ultra-compact microcapacitor comprising a rolled-up layer stack of alternatingly arranged layers of dielectric and/or electrically insulating materials and electrically conductive materials having rolling-up lengths for the rolled-up layer stack of at least 1.0 mm and an absolute electrical storage capacity of at least 10 nF.

2. The ultra-compact microcapacitor according to claim 1, wherein the ultra-compact microcapacitor has an absolute electrical storage capacity between 0.05 and 1 F.

3. The ultra-compact microcapacitor according to claim 1, wherein the rolled-up layer stack has a diameter of from 10 to 100 m.

4. The ultra-compact microcapacitor according to claim 1, wherein rolling-up lengths for the rolled-up layer stack are 1 to 30 mm.

5. The ultra-compact microcapacitor according to claim 1, wherein the layer stack comprises a layer of at least one dielectric and/or electrically insulating material, a layer of at least one first electrically conductive material, an additional layer of at least one dielectric and/or electrically insulating material, and a layer of at least one second electrically conductive material, and in which layer stack the layers of the dielectric and/or electrically insulating material essentially completely cover the layers of the electrically conductive material.

6. The ultra-compact microcapacitor according to claim 5 wherein additional layers of the dielectric and/or electrically insulating material and layers of the electrically conductive material are arranged alternatingly one on top of the other.

7. A method for the production of an ultra-compact microcapacitor comprising applying at least one layer containing a water-soluble cellulose derivate and/or one layer containing a water-soluble polymer to a substrate; on which layer a layer of at least one dielectric and/or electrically insulating material is arranged, on which a layer of at least one first electrically conductive material is arranged, on which a layer of at least one dielectric and/or electrically insulating material is arranged, on which a layer of at least one second electrically conductive material is arranged, and on which a layer of at least one dielectric and/or electrically insulating material is arranged; wherein the layers of the dielectric and/or electrically insulating material are applied such that they essentially completely cover the layers of the electrically conductive material; and wherein subsequently the layer containing a water-soluble cellulose derivate and/or the layer containing a water-soluble polymer is essentially completely removed from the substrate by means of water and/or an organic solvent and/or an organic solvent mixture; and the layer stack is rolled up at a rolling-up speed of more than 0.1 mm/min.

8. The method according to claim 7 wherein additional layers of the dielectric and/or electrically insulating material and layers of the electrically conductive material are arranged alternatingly one on top of the other.

9. The method according to claim 7 wherein methylcellulose is used as a water-soluble cellulose derivate.

10. The method according to claim 7 wherein polyvinyl alcohol and/or polyacrylic acid are used as a water-soluble polymer.

11. The method according to claim 7 wherein, before the removal of the layer containing a water-soluble cellulose derivate and/or the layer containing a water-soluble polymer from the substrate, the other layer materials of the layer stack are partially removed at least on one partial region of this layer.

12. The method according to claim 11 wherein the partial removal of the layer materials of the layer stack is carried out by means of an HF solution or a diluted HF solution or mechanically.

13. The method according to claim 7 wherein the removal of the layer containing a water-soluble cellulose derivate and/or the layer containing a water-soluble polymer is carried out by means of water.

14. The method according to claim 7, wherein the dielectric and/or insulating layer comprises at least one of Al.sub.2O.sub.3, SiO.sub.2, AlTiO.sub.x, SiTiO.sub.x, HfO.sub.x, TaO.sub.x, ZrO.sub.x, HfSiO.sub.x, ZrSiO.sub.x, TiZrO.sub.x, TiZrWO.sub.x, TiO.sub.x, SrTiO.sub.x, PbTiO.sub.x, SiAlO.sub.x, a metal nitride, a silicon nitride, AlScN.sub.y, a metal oxynitride, a silicon oxynitride HfSiO.sub.xN.sub.y or SiC.sub.zO.sub.xN.sub.y.

15. The method according to claim 7 wherein the dielectric and/or insulating layers are applied by means of atomic layer deposition and/or chemical vapor deposition.

16. The method according to claim 7 wherein ethanol is used as an organic solvent.

17. The method according to claim 7 wherein the rolling-up speed achieved is between 0.1 and 5 mm/min.

18. The method according to claim 7 wherein the dielectric and/or insulating layer comprises at least one of AlO.sub.x, SiO.sub.x, AlN.sub.y, SiN.sub.y, AlO.sub.xN.sub.y, or SiO.sub.xN.sub.y.

Description

EXAMPLE

(1) For the production of an ultra-compact microcapacitor having a length of 20 mm and a width of 0.8 mm, a layer of methylcellulose at a concentration of 1 mg/mL water is spun in a completely covering manner onto a silicon substrate having a 1-m thick thermal silicon dioxide layer in a centrifuge at a rotational speed of 4500 rpm, and is subsequently baked and dried on a hot plate for 5 minutes at 120 C. This methylcellulose layer with a thickness typically less than 5 nm is the sacrificial layer. Then, using the method of atomic layer deposition, an 11-nm thick Al.sub.2O.sub.3 layer is deposited at 150 C. such that it completely covers the methylcellulose layer. This Al.sub.2O.sub.3 layer, which acts as a dielectric, also serves as an insulation layer between the two metallic electrodes following the rolling-up and as protection for the sacrificial layer against the subsequent process steps and air humidity.

(2) With the aid of optical photolithography, the first electrode of the capacitor is deposited as one tensioned electrically conductive layer each composed of 15 nm Ti and subsequently 20 nm Cr by means of electron beam evaporation at a rate of 0.1 nm/s in each case.

(3) Then, a second 11-nm thick Al.sub.2O.sub.3 layer is once again deposited by means of atomic layer deposition at 150 C. such that it completely covers the electrically conductive layers.

(4) After optical lithography for the second electrode, the deposition of the second electrically conductive layer of 10 nm Cr takes place at a rate of 0.1 nm/s.

(5) Finally, again using optical lithography, a region across the entire width of the layer stack is marked at one of the narrow ends, in which region the oxide covering the layer stack is removed with reactive-ion etching for 5 min. An RF power of 200 W is thereby applied, with a gas flow of 34 sccm (sccm=standard cm.sup.3/min) CF.sub.4 and 16 sccm CHF.sub.3 at a process pressure of 6 Pa and a substrate temperature of 35 C.

(6) Water is subsequently applied to the now exposed sacrificial layer, whereby the layer of methylcellulose is dissolved, and the tensioned layer stack is rolled up at a speed of 2 mm/min.

(7) An ultra-compact microcapacitor produced in such a manner has, as a rolled up layer stack, a diameter of 80 m and thereby an absolute electrical storage capacity of 0.2 F with a footprint of 80080 m.sup.2.