Method for producing an atom trap, and atom trap

Abstract

A method for producing an atom trap (20) comprising the steps: (a) applying an electrically conductive starting layer (2) onto a substrate (1), (b) applying at least one electric conductor element (4) to the starting layer (2) by means of electro-chemical deposition and/or a lift-off method, (c) applying at least one contacting element (6) by means of electro-chemical deposition and/or a lift-off method, such that the at least one contacting element (6) is connected to the at least one electric conductor element (4) in an electrically conductive manner, (d) removing the starting layer (2) in regions in which no electric conductor element (4) has been applied, (e) applying an insulation layer (7) that at least partially covers the at least one electric conductor element (4) and the at least one contacting element (6), (f) planarizing the insulation layer (7) and exposing the at least one contacting element (6), and (g) applying at least one additional electric conductor (14) element by means of electro-chemical deposition and/or a lift-off method, such that the at least one additional electric conductor element (14) is connected to the at least one contacting element (6) in an electrically conductive manner.

Claims

1. A method for producing an atom trap comprising the steps: (a) applying an electrically conductive starting layer onto a substrate, (b) applying at least one electric conductor element to the starting layer by means of electro-chemical deposition and/or a lift-off method, (c) applying at least one contacting element by means of electro-chemical deposition and/or a lift-off method, such that the at least one contacting element is connected to the at least one electric conductor element in an electrically conductive manner, (d) removing the starting layer in regions in which no electric conductor element has been applied, (e) applying an insulation layer that at least partially covers the at least one electric conductor element and the at least one contacting element, (f) planarizing the insulation layer and exposing the at least one contacting element, and (g) applying at least one additional electric conductor element by means of electro-chemical deposition and/or a lift-off method, such that the at least one additional electric conductor element is connected to the at least one contacting element in an electrically conductive manner.

2. A method for producing an atom trap comprising the steps: (a) applying an electrically conductive starting layer onto a substrate, (b) applying at least one electric conductor element to the starting layer by means of electro-chemical deposition and/or a lift-off method, (c) removing the starting layer in regions in which no electric conductor element has been applied, (d) applying an insulation layer that at least partially, but especially fully, covers the at least one electric conductor element, (e) removing the insulation layer in predetermined regions above the at least one electric conductor element, such that the at least one electric conductor element is partially exposed, (f) applying contacting elements by means of electro-chemical deposition and/or a lift-off method in the regions in which the at least one electric conductor element is exposed, and (g) applying at least one additional electric conductor element by means of electro-chemical deposition and/or a lift-off method, such that the at least one additional electric conductor element is connected to the at least one contacting element in an electrically conductive manner.

3. The method according to claim 1, wherein the electric conductor elements and/or the contacting elements are com-posed of gold or copper, or an alloy containing gold and/or copper.

4. The method according to claim 1, further comprising: exposing the at least one contacting element by planarizing the insulation layer in step (f).

5. The method according to claim 1, further comprising: (h) removing the starting layer in regions in which no additional electric conductor element has been applied, such that gaps form.

6. The method according to claim 4 wherein the gaps have an aspect ratio of at least 1.

7. The method according to claim 1, further comprising: repeating steps (c) to (g) or (c) to (h), thereby obtaining a multilayer atom trap.

8. The method according to claim 1, wherein the electric conductor elements are applied with a layer thickness of at least 1 μm and/or the insulation layer and/or the at least one contacting element is applied with a layer thickness of at least 1 μm.

9. The method according to claim 1, wherein the electric conductor elements and/or the contacting elements are applied with an aspect ratio of at least 1.

10. The method according to claim 1, wherein the substrate features a recess for passing an atomic beam or such a recess is introduced into the substrate.

11. An atom trap, produced according to a method according to claim 1, wherein the atom trap comprises at least one electric conductor element applied by electro-chemical deposition and/or a lift-off method, and at least one contacting element applied by electro-chemical deposition and/or a lift-off method, and the at least one electric conductor element and the at least one contacting element has a layer thickness of at least 1 μm and an aspect ratio of at least 1.

Description

(1) In the following, embodiments of the invention will be explained by way of the attached figures. They show

(2) FIG. 1 the first part of a visualization of the sequence of a method according to the invention for producing an atom trap,

(3) FIG. 2 the second part of a visualization of the sequence of a production method according to the invention,

(4) FIG. 3 a schematic representation of an atom trap according to the invention,

(5) FIG. 4 a schematic representation of a further embodiment of an atom trap according to the invention with a recess for passing an atomic beam and substrate through-contacting elements, and

(6) FIG. 5 a section of a schematic sectional representation of a multilayer atom trap according to the invention.

(7) FIGS. 1 and 2 feature a schematic depiction of a production method according to the invention.

(8) In FIG. 1, the starting layer 2, which is metallic in this case, has already been applied to the substrate 1, in particular across the entire surface and by means of vapor deposition. Photoresist 3 is then applied to said starting layer, especially by means of spincoating or spray-coating.

(9) The photoresist is preferably either a negative or positive resist. In the case of a positive resist, a mask is used which is translucent at the points where the subsequent electric conductor elements 4 (4.1, 4.2) are to be arranged. Exposure makes the positive resist liquid or soluble in the exposed areas so that it can be removed in these regions. The photoresist subsequently remains only in the regions in which electric conductor elements 4 are not to be applied. It thus acts as a mould or template for the application of the at least one electric conductor element 4.

(10) In the case of a negative resist, the regions of the mask that are translucent are those in which the subsequent electric conductor elements 4 are not to be applied. In these regions, the photoresist 3 hardens when exposed. In the non-exposed regions, it can therefore be removed, resulting again in a mould or template for the application of the at least one electric conductor element 4.

(11) In FIG. 1, two electric conductor elements 4.1 and 4.2 have been applied. They are spatially separated from each other and are initially connected to one another in an electrically conductive manner via the starting layer 2.

(12) During the galvanic deposition of the electric conductor elements 4.1 and 4.2, the starting layer 2 acts as a counter-electrode.

(13) Additional photoresist 3 is subsequently applied, which acts as a mould or template for the contacting elements 6. The previously applied photoresist can be removed beforehand. However, it is also possible to apply the additional photoresist to the existing photoresist, i.e. the latter is not removed beforehand.

(14) The contacting elements 6, in the present case the three contacting element 6.1 to 6.3, are subsequently applied by way of electrolytic deposition in the regions that contain no photoresist 3.

(15) The photoresist 3 is then removed, especially completely removed. This may be achieved using a suitable solvent, such as acetone.

(16) In addition, the starting layer 2 is removed in the areas in which no conductor elements 4 have been applied to it. It is preferably possible to remove the starting layer 2 and the photoresist 3 in a single process step.

(17) Alternatively, the starting layer 2 can be removed prior to applying the contacting elements 6.

(18) An insulation layer 7 is subsequently applied. In the present case, this is composed of a polyimide and is applied by means of spin-coating. Preferably, the insulation layer completely covers the previously applied structures. Due to the different heights of the individual structures in relation to the substrate 1, the insulation layer exhibits a structure that corresponds especially to the structures lying beneath it. The height of the insulation layer, i.e. the distance between surface and the underlying structure, is preferably almost constant. This is indicated as h1 in FIG. 1. However, the absolute height of the insulation layer above the substrate varies and leads to the described corresponding structure.

(19) To remove this interfering structure of the insulation layer, the insulation layer 7 is subsequently planarized. It is preferably planarized by means of chemical-mechanical polishing, such that it preferably then has a constant height h2 above the substrate 1. Consequently, material of the insulation layer is removed.

(20) In the embodiment shown, the insulation layer 7 is only planarized so far, i.e. only so much material is removed, that the contacting elements 6.1 to 6.3 are still covered by the insulation layer 7. In particular, the height of this layer covering the contacting elements 6.1 to 6.3 is as low as possible. It is preferably less then 250 nm.

(21) Photoresist 3 is subsequently reapplied, leaving out the regions below which the contacting elements 6.1 to 6.3 can be found. In these omitted regions, the insulation layer is removed, for example by etching or a suitable solvent. Preferably, a removal method is used that does not affect the contacting elements 6.

(22) In the regions of the insulation layer 7 covered by the photoresist 3, the height is still the height h2, which is in particular constant.

(23) An additional electrically conductive starting layer 12 is then applied to the insulation layer 7 and the exposed contacting elements 6.1 to 6.3.

(24) Photoresist 3 is subsequently reapplied to said starting layer, which acts as a mould or template for the additional electric conductor elements 14.1 and 14.2. These are applied to the additional starting layer 12 by means of electro-chemical deposition.

(25) The photoresist is subsequently removed. The additional starting layer 12 is also removed in the regions in which no additional electric conductor element 14 has been applied. This is done in two separate steps or preferably in one process step.

(26) In the regions where the photoresist 3 and the starting layer 2 have been removed, the insulation layer 7 is now exposed. This insulation layer is also subsequently removed, for example through etching, thereby producing gaps 8. These gaps are restricted at the bottom by the electric conductor elements 4 and/or the substrate. In the present case, the gap 8.1 is restricted by the electric conductor element 4.1. The gap 8.2 indicated at the edge, however, is restricted by the substrate 1.

(27) Additional contacting elements 16 can be subsequently applied to the conductor elements 14 to obtain a multilayer atom trap. The process steps outlined above can be repeated several times.

(28) It is also possible to conduct the depicted method only in certain regions of the substrate 1. Furthermore, it is also possible to conduct the method in several different regions of the same substrate 1.

(29) FIG. 3 shows such an atom trap 20 according to the invention. In it, several multilayer and spatially separated conductor structures 21 to 23 are schematically depicted. They have been applied to the substrate according to the method outlined in FIGS. 1 and 2. The conductor structures 21 to 23 are preferably not conductively connected to one another and they each comprise their own electrical connection 29 for the purposes of electrical current supply.

(30) The conductor structures 21 to 23 serve to generate an electric field, especially an inhomogeneous electric field, above the atom trap. In the present case, ions 24.1 to 24.3 are trapped and stored in said field. These ions were previously generated from neutral atoms by means of photoionization. A laser beam 25 is deployed for photoionization.

(31) The multilayer conductor structures 21.i (where i=1, 2) are connected to a DC voltage. The conductor structures 22.1 and 22.3 are connected to an AC voltage and the conductor structures 23.1 and 23.2 are grounded. However, it is also possible for the conductor structures 23 to be connected to a DC voltage that is different to 0.

(32) FIG. 4 schematically depicts a further embodiment of an atom trap 20 according to the invention. This atom trap also features multilayer conductor structures 21 to 23, wherein a recess 26 in the form of a duct has also been introduced in the substrate 1. An atomic beam 27 is guided through this recess.

(33) The atomic beam 27 can be generated by heating a metal wire, for instance by heating a beryllium wire at specific points to over 1000 K.

(34) In the present case, atoms of the atomic beam are transformed into ions 24.1 to 24.3 by photoionization, which are stored in the electric field generated by the multilayer conductor structures 21 to 23.

(35) The substrate also features substrate through-contacting elements 28, via which the multilayer conductor structures 21 to 23 are supplied with an electrical current. Preferably, at least one substrate through-contracting element 28 is assigned to each multilayer conductor structure 21 to 23. By means of the substrate through-contacting elements 28, an electrical current can be supplied very easily from the back of the substrate 1.

(36) FIG. 5 depicts an exemplary sectional representation of a multilayer atom trap. The sectional representation corresponds to the atom trap from the production method depicted in FIGS. 1 and 2. Additional contacting elements 16.1 and 16.2 have been applied by means of electro-chemical deposition to the most recently applied conductor elements 14.1 and 14.2. They are preferably identical in dimension to the contacting elements 6.1 to 6.3. In the regions where no additional contacting element 16 has been applied to the additional electric conductor elements 14.1 and 14.2, an additional insulation layer 17 has been applied via spin-coating. In FIG. 5, the contacting elements are exposed and an additional starting layer, not shown, follows, which is supported on the additional contacting elements 16.1 and 16.2 and the additional insulation layer 17.

(37) FIG. 5 shows that the aspect ratio, i.e. the ratio of the width to the height of the gaps 8.1 and 8.2 increases with the application of additional layers. The gaps 8.1 and 8.2 in FIG. 5 therefore exhibit a greater height than in FIG. 2, which leads to a greater aspect ratio if the width remains the same.

REFERENCE LIST

(38) 1 substrate 2 starting layer 3 photoresist 4 electric conductor element 6 contacting element 7 insulation layer 8 gap 12 additional starting layer 14 additional electric conductor element 16 additional contacting element 17 additional insulation layer 20 atom trap 21 multilayer conductor structure, connected to a DC voltage 22 multilayer conductor structure, connected to an AC voltage 23 multilayer conductor structure, grounded 24 ion 25 laser beam 26 recess 27 atomic beam 28 substrate through-contacting element 29 electrical connection h height