Method and structure of monolithically integrated IC-MEMS oscillator using IC foundry-compatible processes
First Claim
1. A method for fabricating a monolithic integrated circuit and MEMS resonator device, the method comprising:
- providing a first semiconductor substrate having a first surface region;
forming one or more CMOS integrated circuit device provided on a CMOS integrated circuit device region overlying the first surface region, the CMOS integrated circuit device region having a CMOS surface region;
forming a dielectric layer overlying the CMOS surface region;
joining a second semiconductor substrate having a second surface region to the CMOS surface region by bonding the second surface region to the dielectric layer;
thinning the second semiconductor substrate to a desired thickness while maintaining attachment to the dielectric layer;
forming one or more via structures within one or more portions of the desired thickness of the second semiconductor substrate;
forming a conformal coating of metal material within the one or more via structures;
forming one or more free standing MEMS structures within one or more portions of the desired thickness of the second semiconductor substrate, the one or more MEMS structures being configured to be supported by one or more members integrally formed on the desired thickness of the second semiconductor substrate to cause the one or more MEMS structures to move in an oscillating manner characterized by a frequency range; and
forming a sacrificial layer overlying the one or more free standing MEMS structures.
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Abstract
The present invention relates to integrating an inertial mechanical device on top of an IC substrate monolithically using IC-foundry compatible processes. The IC substrate is completed first using standard IC processes. A thick silicon layer is added on top of the IC substrate. A subsequent patterning step defines a mechanical structure for inertial sensing. Finally, the mechanical device is encapsulated by a thick insulating layer at the wafer level. Compared with the incumbent bulk or surface micromachined MEMS inertial sensors, vertically monolithically integrated inertial sensors provided by embodiments of the present invention have one or more of the following advantages: smaller chip size, lower parasitics, higher sensitivity, lower power, and lower cost.
23 Citations
20 Claims
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1. A method for fabricating a monolithic integrated circuit and MEMS resonator device, the method comprising:
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providing a first semiconductor substrate having a first surface region; forming one or more CMOS integrated circuit device provided on a CMOS integrated circuit device region overlying the first surface region, the CMOS integrated circuit device region having a CMOS surface region; forming a dielectric layer overlying the CMOS surface region; joining a second semiconductor substrate having a second surface region to the CMOS surface region by bonding the second surface region to the dielectric layer; thinning the second semiconductor substrate to a desired thickness while maintaining attachment to the dielectric layer; forming one or more via structures within one or more portions of the desired thickness of the second semiconductor substrate; forming a conformal coating of metal material within the one or more via structures; forming one or more free standing MEMS structures within one or more portions of the desired thickness of the second semiconductor substrate, the one or more MEMS structures being configured to be supported by one or more members integrally formed on the desired thickness of the second semiconductor substrate to cause the one or more MEMS structures to move in an oscillating manner characterized by a frequency range; and forming a sacrificial layer overlying the one or more free standing MEMS structures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of forming a monolithic MEMS and integrated circuit device, the method comprising;
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providing a first semiconductor substrate having a first surface region; forming one or more CMOS integrated circuit device provided on a CMOS integrated circuit device region overlying the first surface region, the CMOS integrated circuit device region having a CMOS surface region; forming a dielectric layer overlying the CMOS surface region; joining a second semiconductor substrate having a second surface region to the CMOS surface region by bonding the second surface region to the dielectric layer, thinning the second semiconductor substrate to a desired thickness while maintaining attachment to the dielectric layer; forming one or more MEMS structures within one or more portions of the desired thickness of the second semiconductor substrate; and forming a sacrificial layer overlying the one or more free standing MEMS structures. - View Dependent Claims (19, 20)
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Specification