Abstract: A process comprises reducing the thickness of a substrate carrying a plurality of devices, with at least certain of the devices having a micro-machined mesh. A carrier wafer is attached to the back side of the substrate and the fabrication of the devices is completed from the top side of the substrate. Thereafter the plurality of devices is singulated. Various alternative embodiments are disclosed which demonstrate that the thinning of the wafer may occur at different times during the process of fabricating the MEMS devices such as before the mesh is formed or after the mesh is formed. Additionally, the use of carrier wafers to support the thinned wafer enables process steps to be carried out on the side opposite from the side having the carrier wafer. The various alternative embodiments demonstrate that the side carrying the carrier wafer can be varied throughout the process.

Abstract: The present invention is directed to a structure comprised of alternating layers of metal and sacrificial material built up using standard CMOS processing techniques, a process for building such a structure, a process for fabricating devices from such a structure, and the devices fabricated from such a structure. In one embodiment, a first metal layer is carried by a substrate. A first sacrificial layer is carried by the first metal layer. A second metal layer is carried by the sacrificial layer. The second metal layer has a portion forming a micro-machined metal mesh. When the portion of the first sacrificial layer in the area of the micro-machined metal mesh is removed, the micro-machined metal mesh is released and suspended above the first metal layer a height determined by the thickness of the first sacrificial layer. The structure may be varied by providing a base layer of sacrificial material between the surface of the substrate and the first metal layer.

Abstract: The present invention is directed to a structure comprised of alternating layers of metal and sacrificial material built up using standard CMOS processing techniques, a process for building such a structure, a process for fabricating devices from such a structure, and the devices fabricated from such a structure. In one embodiment, a first metal layer is carried by a substrate. A first sacrificial layer is carried by the first metal layer. A second metal layer is carried by the sacrificial layer. The second metal layer has a portion forming a micro-machined metal mesh. When the portion of the first sacrificial layer in the area of the micro-machined metal mesh is removed, the micro-machined metal mesh is released and suspended above the first metal layer a height determined by the thickness of the first sacrificial layer. The structure may be varied by providing a base layer of sacrificial material between the surface of the substrate and the first metal layer.

Abstract: The present invention describes a processes that builds an acoustic cavity, a chamber, and vent openings for acoustically connecting the chamber with the acoustic cavity. The dry etch processes may include reactive ion etches, which include traditional parallel plate RIE dry etch processes, advanced deep and inductively coupled plasma RIE processes. Three embodiments for connecting the chamber to the cavity from the top side of the substrate, e.g. by using pilot openings formed using at least a portion of the mesh as an etch mask, by forming the vent openings using at least a portion of the mesh as an etch mask, or by having the chamber intersect the vent openings as the chamber is being formed, illustrate how the disclosed process may be modified. By forming the cavity on the back side of the substrate, the depth of the vent holes is decreased. Additionally, using at least a portion of the micro-machined mesh as an etch mask for the vent holes makes the process self-aligning.

Abstract: A direct digital microphone is constructed of a plurality of first membranes each formed by a micro-machined mesh supported by a substrate. Each of the membranes has a first and a second position. A second membrane is supported by the substrate and positioned above the plurality of first membranes to form a chamber between the plurality of first membranes and the second membrane. A pressure sensor is responsive to pressure in the chamber. Drive electronics are responsive to the pressure sensor for controlling the positions of each of the plurality of first membranes. Output electronics are responsive to the positions of the plurality of first membranes to produce a digital output signal. A stacked membrane structure and methods of fabrication and operation are also disclosed.

Abstract: A method for fabricating a micromachined structure. The method includes forming a circuitry layer having an upper etch-resistant layer on an upper surface of a substrate, directionally etching a portion of the circuitry layer exposed by the upper etch-resistant layer, and directionally etching a portion the substrate exposed by the upper etch-resistant layer with a deep reactive ion etch.