Patent Number: 
Section: claims

1. An apparatus comprising:an electrically conductive substrate having top and bottom surfaces and having vias that cross from the top surface to the bottom surface;a pair of planar first electrodes supported over said top surface; andsecond electrodes having planar surfaces located over said top surface, portions of the planar surfaces being laterally adjacent said planar first electrodes; andwherein one of the second electrodes includes a portion that is located in one of the vias and traverses the substrate. 2. The apparatus of claim 1, wherein the substrate is a doped semiconductor. 3. The apparatus of claim 2, further comprising a dielectric layer located between the second electrodes and the substrate. 4. The apparatus of claim 2, wherein the pair of planar first electrodes are separated by more than 50 micrometers. 5. The apparatus of claim 1,wherein the planar electrodes and second electrodes form plates of a first capacitor;wherein the substrate and the second electrodes form plates of a second capacitor; andwherein a ratio of a capacitance of the second capacitor to a capacitance of the first capacitor is at least as large as 100. 6. The apparatus of claim 5, wherein the ratio of the capacitance of the second capacitor to the capacitance of a first capacitor is at least as large as 500. 7. The apparatus of claim 1, wherein the apparatus is able to trap ions over the planar electrodes in response to the planar electrodes being driven by a voltage having a RF frequency. 8. The apparatus of claim 1, wherein one of the second electrodes is separated from the substrate by 0.5 micrometers or less. 9. The apparatus of claim 1, wherein one of the second electrodes is located between the pair of first electrodes, the one of the second electrodes is separated into segments. 10. The apparatus of claim 9, wherein each segment includes a separate portion that is located in one of the vias and that traverses the substrate. 11. The apparatus of claim 9, wherein one of the second electrodes is surrounded by one or more of the first electrodes. 12. An apparatus, comprising:an electrically conductive semiconductor substrate having a top surface and a bottom surface and having a plurality of planar ion traps; andeach ion trap having first and second electrodes and being configured to trap ions over the top surface of the substrate, each second electrode including a portion that crosses through the substrate. 13. The apparatus of claim 12, wherein the substrate is a doped crystalline semiconductor. 14. The apparatus of claim 13, further comprising a RF driver connected between said substrate and said first electrodes. 15. The apparatus of claim 13, wherein in one of the ion traps, the first electrodes and second electrodes form plates of a first capacitor;wherein in the one of the ion traps, the substrate and the second electrodes form plates of a second capacitor; andwherein a ratio of a capacitance of the second capacitor to a capacitance of the first capacitor is at least as large as 100. 16. The apparatus of claim 13, wherein the substrate is a metal. 17. The apparatus of claim 12, further comprising:a second substrate having a top surface disposed adjacent the bottom surface of the first substrate, the second substrate having circuits for controlling said ion traps and being disposed to make physical and electrical connection with said portions. 18. The apparatus of claim 17, wherein the circuits of the second substrate comprise gates and RF filters. 19. The apparatus of claim 12, wherein a first one of said ion traps is configured to trap an ion at a first trap height above the top surface and a second one of said ion traps is configured to trap the ion at a different second trap height above the top surface.