Microfabricated system for magnetic field generation and focusing
First Claim
1. A micro-coil device for the generation, focusing and manipulation of magnetic fields comprising:
- a substrate having an upper and a lower surface;
a planar micro-coil, formed of a plated conductor having an aspect ratio greater than 3/1, said micro-coil being formed in a variety of geometrical shapes on the upper surface of said substrate or in a trench formed through said upper surface and said micro-coil having at least two ends;
a passivating oxide layer formed over said micro-coil;
a dielectric layer formed over said oxide layer; and
bonding pads for making electrical connections to said micro-coil formed on said coil ends or on conducting leads connected to said coil ends.
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Accused Products
Abstract
A method of forming, in or on a Si substrate, planar micro-coils with coil windings of high aspect ratio (>3) and a wide variety of geometric shapes. The micro-coils may be formed on a Si substrate and be embedded in a dielectric, or they may be formed in trenches within a Si substrate. The micro-coils may have field enhancing ferromagnetic pillars rising above the micro-coil plane, formed at positions of maximum magnetic field strength and the micro-coils may also include magnetic layers formed beneath the substrate and contacting the pillars to form a substantially closed pathway for the magnetic flux. The substrate may be thinned to membrane proportions. These micro-coils produce strong magnetic fields with strong field gradients and can be used in a wide variety of processes that involve the exertion of strong magnetic forces at small distances or the creation of magnetic wells for trapping and manipulating small particles.
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Citations
79 Claims
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1. A micro-coil device for the generation, focusing and manipulation of magnetic fields comprising:
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a substrate having an upper and a lower surface;
a planar micro-coil, formed of a plated conductor having an aspect ratio greater than 3/1, said micro-coil being formed in a variety of geometrical shapes on the upper surface of said substrate or in a trench formed through said upper surface and said micro-coil having at least two ends;
a passivating oxide layer formed over said micro-coil;
a dielectric layer formed over said oxide layer; and
bonding pads for making electrical connections to said micro-coil formed on said coil ends or on conducting leads connected to said coil ends. - View Dependent Claims (2, 3, 4, 5, 6, 19, 22)
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7. A micro-coil device that includes a dielectric embedded micro-coil, for the generation, focusing and manipulation of magnetic fields comprising:
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a substrate having an upper and a lower surface;
a planar linear micro-coil, formed of a plated conductor having an aspect ratio greater than 3/1, formed in a variety of geometrical shapes on the upper surface of said substrate, said coil having at least two ends;
a dielectric layer formed over said micro-coil and conformally covering said micro-coil; and
bonding pads for making electrical connections to said micro-coil, connected to said coil ends or to conducting leads that are connected to said coil ends. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 23, 24)
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25. A micro-coil device having a micro-coil, a ferromagnetic pillar and a ferromagnetic backplate for the generation, focusing and manipulation of magnetic fields comprising:
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a substrate having an upper and a lower surface;
a planar linear micro-coil, formed of a plated conductor having an aspect ratio greater than 3/1, said micro-coil being formed in a variety of geometrical shapes on the upper surface of said substrate or in a trench formed through said upper surface, said coil having at least two ends;
a cavity within the substrate, said cavity formed through an opening in the lower surface of said substrate and said cavity having sides and an upper surface within said substrate;
a ferromagnetic plated layer formed conformally filling said cavity, a lower surface of said layer being substantially co-planar with the lower surface of the substrate and an upper surface of said layer contacting the upper surface of said cavity;
an opening formed through the upper surface of the substrate, said opening extending through the substrate and exposing a portion of said ferromagnetic layer upper surface;
a ferromagnetic plated pillar formed within said opening, a lower end of said pillar contacting said exposed portion of the ferromagnetic layer and an upper end of said pillar extending above said substrate upper surface;
bonding pads for making electrical connections to said micro-coil connected to the ends of said micro-coil or to conducting leads that are connected to the ends of said micro-coil. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. A method of forming a micro-coil device for the generation, focusing and manipulation of magnetic fields comprising:
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providing a substrate having upper and lower surfaces;
forming a geometrically patterned linear trench of depth d and width w, wherein d/w>
3, through said upper surface, said trench having side and bottom surfaces and at least two ends, said trench to be used in the formation of a micro-coil;
forming a grid of orthogonally intersecting trenches at the ends of said linear trench and at positions peripherally disposed thereto, said grid of trenches to be used in the formation of inner bonding pads and minor and major outer bonding pads;
conformally covering said upper surface and the side and bottom surfaces of said linear trench and said grid of trenches with a three-layer sequential deposition further comprising;
forming a first layer of oxide to a thickness to;
forming on said first oxide layer a barrier layer to a thickness tb;
forming on said barrier layer a seed layer to a thickness ts;
forming a first layer of conductor over said upper substrate surface, said layer also conformally covering said three layer deposition and filling all said trenches in a void-free manner;
removing that portion of said first conductor layer and sequential three-layer deposition that lies on the upper substrate surface, retaining that portion of said first conductor layer within said trenches, forming, thereby, a micro-coil conformally filling the trench, having ends that correspond to the ends of the trench and having an upper surface that is co-planar with the upper substrate surface and also forming a conductor filled mesh within each of said grid of trenches;
forming a second layer of oxide on said upper substrate, mesh and micro-coil surfaces, said layer being a passivation layer;
removing a portion of said second oxide layer above each mesh whereat subsequent electrical connections will be made, exposing clean conductor surfaces at those positions;
forming a second layer of conducting material on said second oxide layer, said second layer of conducting material contacting said mesh, said layer electrically contacting said micro-coil and forming a bonding-pad and said layer extending between bonding-pads;
coating the upper surface of the substrate and said bonding pads with a layer of dielectric polymer;
removing a portion of said polymer layer over the bonding pad. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. A method of forming a dielectric-embedded micro-coil and pillar device for the generation, focusing and manipulation of magnetic fields comprising:
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providing a substrate having an upper and a lower surface;
forming a patterned layer of conductor over the upper substrate surface, said layer to act as a base for a subsequent plating process;
forming a first dielectric layer, to a thickness t1, over the upper substrate surface and said patterned conductor layer;
forming an opening through the first dielectric layer, said opening exposing an upper surface of the patterned conductor layer;
plating by an electroless process, within said opening, a first portion of a ferromagnetic pillar on the patterned conductor layer, the height of said first pillar portion being t1, the thickness of said first dielectric layer;
removing the first dielectric layer;
depositing a seed layer on the substrate surface, said seed layer being disposed about the patterned conductor layer, being thinner than said patterned conductor layer and being contiguous with it;
forming a second dielectric layer over the seed layer, the thickness of the second dielectric layer being t2, which is greater than t1;
forming a micro-coil trench through said second dielectric layer, said trench being patterned in a linear geometric shape having at least two ends, said trench terminating at said seed layer and said trench having a width w2 that produces an aspect ratio of t2/w2>
3;
forming an array of trenches at the ends of said micro-coil trench and at positions peripherally disposed thereto, said array of trenches to be used in the formation of bonding pads;
forming a micro-coil by electroplating, on said seed layer, a void-free conducting layer conformally filling said trench, said micro-coil having ends corresponding to said trench ends and said conducting layer also filling said array of trenches to form a mesh;
removing a portion of the second dielectric layer above the pillar, exposing, thereby, an upper surface of said pillar;
forming, by electroless plating, a second pillar portion on said exposed first pillar portion upper surface, the total height of said first and second pillar portions being t4;
removing the second dielectric layer and the seed layer, leaving only those portions of the seed layer that are beneath said micro-coil;
forming a third dielectric layer with thickness t3 that is greater than t2 but less than t4, said third layer thereby conformally covering said micro-coil but not completely covering said second pillar portion;
forming openings in the third dielectric layer over said mesh, thereby exposing said mesh;
cleaning said mesh; and
forming an electrically conducting layer in said openings, the layer electrically contacting said mesh and forming a bonding pad. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. A method of forming a dielectric-embedded micro-coil device for the generation, focusing and manipulation of magnetic fields comprising:
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providing a substrate having an upper and a lower surface;
depositing a seed layer on the substrate surface;
forming a first dielectric layer over the seed layer, the thickness of the first dielectric layer being t1;
forming a micro-coil trench through said first dielectric layer, said trench being patterned in a linear geometric shape having at least two ends, said trench terminating at said seed layer and said trench having a width w1 that produces an aspect ratio of t1/w1>
3;
forming an array of trenches at the ends of said micro-coil trench and at positions peripherally disposed thereto, said array of trenches to be used in the formation of bonding pads;
forming a micro-coil by electroplating, on said seed layer, a void-free conducting layer conformally filling said trench, said micro-coil having ends corresponding to said trench ends and said conducting layer also filling said array of trenches to form a mesh;
removing the first dielectric layer and the seed layer, leaving only those portions of the seed layer that are beneath said micro-coil and mesh;
forming a second dielectric layer with thickness t2 that is greater than t1, said second dielectric layer thereby conformally covering said micro-coil and mesh;
forming openings in the second dielectric layer over said mesh, thereby exposing said mesh;
cleaning said mesh; and
forming an electrically conducting layer in said openings, the layer electrically contacting said mesh and forming a bonding pad. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64)
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65. A method of forming a micro-coil, pillar and backplate within a substrate comprising:
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providing a substrate having an upper and lower surface;
forming, through said upper surface, a linear, geometrically patterned micro-coil trench having at least two ends, having a depth d and width w, wherein the aspect ratio, d/w is greater than 3;
forming an array of trenches at the ends of said micro-coil trench and at positions peripherally disposed thereto, said array of trenches to be used in the formation of bonding pads;
conformally covering said upper substrate surface and the interior of said micro-coil trench and array of trenches with a three-layer sequential deposition further comprising;
forming a first layer of oxide to a thickness to;
forming on said first oxide layer a barrier layer to a thickness tb;
forming on said barrier layer a seed layer to a thickness ts;
forming a layer of conductor over said seed layer, said conductor layer also conformally filling the trenches in a void-free manner;
removing that portion of the conductor that lies on the upper substrate surface, retaining that portion of the conductor within the micro-coil trench and array of trenches, forming, thereby, a micro-coil conformally filling the trench, having ends that coincide with the ends of the trench and having an upper surface that is co-planar with the upper substrate surface and also forming a mesh within the array of trenches;
forming a second oxide layer over said substrate surface and co-planar micro-coil and mesh surfaces;
forming a cavity through the lower surface of said substrate, said cavity extending from the lower surface towards the upper surface and penetrating into the interior of the substrate to an approximate depth tc;
forming a magnetic backplate within said cavity;
forming a plurality of openings within said second oxide layer, a first opening exposing a central portion of said substrate upper surface and the remainder of said openings exposing upper surface portions of the mesh;
cleaning the upper surface portions of said mesh; and
forming an electrically conducting layer in said openings, the layer electrically contacting said mesh and forming a bonding pad;
forming a dielectric layer of thickness td over the upper surface of said oxide layer, said dielectric layer having an upper surface;
forming a second trench extending vertically through said dielectric layer, said trench passing through the first opening in the oxide layer, through the Si substrate and terminating at the upper surface of said backplate, whereat it exposes a corresponding portion of said backplate upper surface;
forming an electroless plated pillar conformally filling said second trench, said pillar being plated onto said exposed upper surface portion of the backplate, said pillar extending vertically upward from the backplate and terminating at the upper surface of said dielectric layer; and
thenremoving the dielectric layer. - View Dependent Claims (66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
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79. A method of micro-self-assembly using micro-coils comprising:
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providing a plurality of micro-components;
providing a substrate having a plurality of receptor sites at which said micro-components are to be positioned and affixed;
coating at least a portion of said micro-components with a magnetic material, making said micro-components subject to magnetic forces;
positioning a plurality of micro-coils at locations on or within said substrate, a first portion of said micro-coils being positioned at said receptor sites, and a second portion of said micro-coils being positioned along paths leading to said receptor sites, said micro-coils capable of producing magnetic fields having gradients and potential wells when electrically energized;
immersing said substrate and said micro-components in a fluid;
sequentially energizing said micro-coils or a set of selected micro-coils, thereby guiding a selected micro-component or a set of such micro-components to a receptor site or set of receptor sites and trapping said micro-components at said receptor site or sites;
affixing, using a bonding process, said micro-component to said receptor site while said micro-coil remains energized.
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Specification