Microfabricated structures with trench-isolation using bonded-substrates and cavities
First Claim
1. A micromechanical device comprising:
- a device substrate having a first surface, a second surface, and a semiconductor layer;
a handle substrate having a first surface and a second surface, the first surface of the device substrate bonded to the first surface of the handle substrate;
at least a first trench formed in the device substrate, said at least first trench extending from the second surface of the device substrate through the device substrate towards the handle substrate;
a dielectric within the first trenches;
at least one cavity formed in at least one of said substrates and disposed below the second surface of the device substrate, said cavity enclosing at least a portion of said at least one first trench;
at least a second trench formed in the second surface of the device substrate, the at least second trench defining at least one micromechanical device.
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Accused Products
Abstract
A microstructure and method for forming the microstructure are disclosed. The method includes: providing a handle substrate; providing a device substrate in which high-aspect-ratio structures and optional integrated circuitry will be fabricated; forming one or more filled isolation trenches within a recessed cavity on a first surface of the device substrate or alternatively forming one or more filled isolation trenches on a first surface of the device substrate and forming a recessed cavity on a first surface of the handle substrate; bonding the first surface of the device substrate to the first surface of the handle substrate; removing a substantially uniform amount of material from the second surface of the device substrate to expose at least one isolation trench; optionally forming circuits and interconnection on a second surface of the device substrate; and etching a set of features in the second surface of the device substrate to complete the definition of electrically isolated structural elements.
The micromechanical device includes: a device substrate having a first surface, a second surface, and a semiconductor layer; a handle substrate, the first surface of the device substrate bonded to the handle substrate; one or more first trenches formed in the device substrate, the first trenches extending from the second surface of the device substrate through the device substrate towards the handle substrate; a dielectric within the first trenches; one or more cavities disposed below the second surface of the device layer, a cavity enclosing a portion of at least one trench; at least one second trench formed in the second surface of the device substrate, the second trench completing definition of one or more micromechanical devices.
249 Citations
23 Claims
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1. A micromechanical device comprising:
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a device substrate having a first surface, a second surface, and a semiconductor layer;
a handle substrate having a first surface and a second surface, the first surface of the device substrate bonded to the first surface of the handle substrate;
at least a first trench formed in the device substrate, said at least first trench extending from the second surface of the device substrate through the device substrate towards the handle substrate;
a dielectric within the first trenches;
at least one cavity formed in at least one of said substrates and disposed below the second surface of the device substrate, said cavity enclosing at least a portion of said at least one first trench;
at least a second trench formed in the second surface of the device substrate, the at least second trench defining at least one micromechanical device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
a dielectric formed upon the second surface of the device substrate, the dielectric including at least one exposed contact region exposing the second surface of the device substrate;
at least one electrical conductor, the electrical conductor interconnecting at least one micromechanical device through said at least one contact region.
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3. The device of claim 1, further including circuitry formed in the second surface of the device layer, the circuitry including at least one transistor.
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4. The device of claim 2 wherein the electrical conductor defines an interconnection over at least one first trench.
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5. The device of claim 1, additionally including circuitry formed upon a micromechanical structure defined by the second trench.
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6. The device of claim 1 wherein the handle substrate comprises a wafer of material chosen from at least one of:
- silicon, silicon dioxide on silicon, silicon nitride on silicon, quartz, glass, and aluminum oxide.
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7. The device of claim 1 wherein the device substrate comprises a wafer of material chosen from at least one of:
- undoped silicon, p-type silicon, n-type silicon, silicon having a thin layer of heavily p-doped silicon on the first surface of the device layer, and silicon having a thin layer of heavily n-doped silicon on the first surface of the device layer.
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8. The device of claim 1 wherein the dielectric comprises a material chosen from at least one of:
- deposited silicon dioxide, TEOS oxide, silicon nitride, phosphosilicate glass, arsenic glass, boron glass, boro-phosphosilicate glass, grown silicon dioxide.
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9. The device of claim 1 wherein said at least one first trench extends into said at least second trench thereby forming a nubbin.
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10. The device of claim 1 wherein said at least one first trench contains one or more condyles.
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11. The device of claim 1 wherein the dielectric substantially fills said at least first trench.
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12. The device of claim 1 further including a second material formed on the dielectric, the second material substantially filling each first trench.
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13. The device of claim 12 wherein said second material includes polysilicon.
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14. The device of claim 1, further including one or more studs.
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15. The device of claim 1, wherein the cavity disposed below the second surface of the device layer is formed into the first surface of the device layer.
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16. The device of claim 1, wherein the cavity disposed below the second surface of the device layer is formed into the first surface of the handle layer.
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17. The device of claim 1 wherein the first surface of the device substrate is anodic-bonded to the first surface of the handle substrate.
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18. The device of claim 1 wherein the first surface of the device substrate is fusion-bonded to the first surface of the handle substrate.
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19. The device of claim 1 further including a layer of silicon dioxide at the bond interface between the first surface of the device substrate and the first surface of the handle substrate.
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20. The device of claim 1 wherein said first trench is tapered toward said second surface.
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21. A device, comprising:
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a device wafer having a first surface and a second surface;
a handle wafer bonded to said device wafer at said first surface;
at least a first trench formed in the device substrate having a taper toward said second surface;
an insulator in said first trench;
at least one cavity formed in at least one of said wafers between said device wafer and said handle wafer; and
at least a second trench formed in said device wafer defining at least one micromechanical device. - View Dependent Claims (22)
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23. A device, comprising:
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a device wafer having a first surface and a second surface;
a handle wafer having a first surface bonded to said device wafer device wafer at said first surface of said device wafer;
at least a first trench formed in the first surface of said device substrate and extending from said first surface through toward said second surface;
a silicon dioxide insulator substantially occupying said first trench;
at least one cavity formed in at least one of said wafers between said device wafer and said handle wafer; and
at least a second trench formed in said device wafer defining at least one micromechanical device.
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Specification