Process for making a semiconductor sensor with a fusion bonded flexible structure
First Claim
1. A process for making a semiconductor device containing a flexible structure, comprising the steps of:
- oxidizing a portion of a surface of a first semiconductor substrate to form a first oxide region and leave an unoxidized region on the surface;
removing the first oxide region to form a depression in the first substrate; and
bonding a second substrate to the unoxidized region of the first substrate so that a portion of the second substrate overlies the depression.
4 Assignments
0 Petitions
Accused Products
Abstract
Fabrication of semiconductor devices with movable structures includes local oxidation of a wafer and oxide removal to form a depression in an elevated bonding surface. A second wafer is fusion bonded to the elevated bonding surface and shaped to form a flexible membrane. An alternative fabrication technique forms a spacer having a depression on a first wafer and active regions on a second wafer, and fusion bonds the wafers together with the depression over the active regions. Devices formed are integrable with standard MOS devices and include FETs, capacitors, and sensors with movable membranes. An FET sensor has gate and drain coupled together and a drain-source voltage which depends on the gate'"'"'s deflection. Selected operating current, channel length, and channel width provide a drain-source voltage linearly related to gate deflection. Alternatively, two transistors subjected to the same gate deflection provide a differential voltage related to the square root of the deflection if channel currents or channel widths differ. Transistors subjected to the different gate deflections provide a differential signal that cancels effects that are independent of deflection. A capacitive sensor includes a doped region underlying the center of a flexible membrane. The doped region is isolated from a surrounding region which is biased at the voltage of the membrane.
76 Citations
35 Claims
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1. A process for making a semiconductor device containing a flexible structure, comprising the steps of:
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oxidizing a portion of a surface of a first semiconductor substrate to form a first oxide region and leave an unoxidized region on the surface; removing the first oxide region to form a depression in the first substrate; and bonding a second substrate to the unoxidized region of the first substrate so that a portion of the second substrate overlies the depression. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for making a semiconductor device containing a flexible structure, the process comprising:
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oxidizing a portion of a surface of a first semiconductor substrate to form a first oxide region and leave an unoxidized region on the surface, wherein the unoxidized region encompasses the first oxide region; removing the first oxide region to form in the first substrate a depression which is encompassed by the unoxidized region; oxidizing the surface of the first substrate to form a second oxide region encompassing the unoxidized region of the surface; removing the second oxide region to leave a mesa containing the depression, on the surface of the first substrate; forming an active region in a portion of the first substrate defined by the depression; and fusion bonding a second substrate to the unoxidized region of the first substrate so that a portion of the second substrate overlies the depression. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A process for making a semiconductor device containing a flexible structure, the process comprising:
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oxidizing a portion of a surface of a first semiconductor substrate to form a first oxide region and leave an unoxidized region on the surface; removing the first oxide region to form a depression in the first substrate; bonding a second substrate to the unoxidized region of the first substrate so that a portion of the second substrate overlies the depression; and shaping the second substrate to form a cantilever over the depression. - View Dependent Claims (21, 22)
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23. A process for making a semiconductor device having a flexible structure, comprising:
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shaping a first semiconductor substrate to form a depression in a first surface of the first semiconductor substrate; forming an active region in a second semiconductor substrate; bonding the first surface of the first substrate to the second substrate so that the depression overlies the active region; and shaping a second surface of the first substrate to form a flexible structure over the active region. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A process for making a semiconductor device having a flexible structure, comprising:
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etching a first substrate to form a mesa; oxidizing the first substrate to form an oxide region on the mesa; removing the oxide region to form the depression in the mesa; forming an active region in a second semiconductor substrate; fusion bonding the first substrate to the second substrate so that the depression overlies the active region; and shaping a second surface of the first substrate to form a flexible structure over the active region. - View Dependent Claims (31)
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32. A process for making a semiconductor device containing a flexible structure, the process comprising:
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shaping a first semiconductor substrate to form a mesa and a depression in a top surface of the mesa, wherein the top surface of the mesa is elevated relative to a surface that surrounds the mesa; forming an active region in a portion of the first semiconductor substrate defined by the depression; and bonding a second substrate to the top surface of the mesa so that a portion of the second substrate overlies the active region. - View Dependent Claims (33, 34, 35)
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Specification