# US 8,569,090 B2 · Wafer level structures and methods for fabricating and packaging MEMS > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,090 B2 - Document ID: US8569090B2 - Status: Granted - Kind: B2 - Application number: 13/306,679 - Filed: 2011-11-29 - Published: 2012-06-07 - Granted: 2013-10-29 - Earliest claimed: 2010-12-03 - Applicants: Babak Taheri - Inventors: Babak Taheri - Web page: https://patentgrep.com/patent/US8569090B2 ## CPC - B81B 7/007: {Interconnections between the MEMS and external electrical signals} - B81C 1/0023: {Packaging together an electronic processing unit die and a micromechanical structure die (MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261)} - B81B 2207/092: Buried interconnects in the substrate or in the lid - B81B 2207/095: through the lid - B81B 2207/096: through the substrate - B81B 2207/097: Interconnects arranged on the substrate or the lid, and covered by the package seal - H10W 72/884: {Die-attach connectors and bond wires} - H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL} - H10W 90/732: {between stacked chips} - H10W 90/752: {between stacked chips} - H10W 90/753: {between laterally-adjacent chips} - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract Methods of fabricating a Micro-Electromechanical System (MEMS) in a hermetically sealed cavity formed at a substrate level are provided. Generally, the method comprises: (i) forming a number of first open cavities in a surface of a first substrate and a number of second open cavities in a surface of a second substrate corresponding to the first open cavities; (ii) forming an actuator/sensor layer including a number of MEMS devices with electrically conductive regions therein; (iii) bonding the first substrate and the second substrate to the actuator/sensor layer so that at least one of the number of the first and second open cavities align with at least one of the number of MEMS devices to form a sealed cavity around the MEMS; and (iv) electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity through an electrical interconnect. Other embodiments are also described. ## Claims ### Claim 1 A method comprising: forming a number of first open cavities in a surface of a first substrate and a number of second open cavities in a surface of a second substrate corresponding to the first open cavities; forming an actuator/sensor layer including a number of Micro-Electromechanical System (MEMS) devices with electrically conductive regions therein; bonding the first substrate and the second substrate to the actuator/sensor layer so that at least one of the number of the first and second open cavities align with at least one of the number of MEMS devices to form a hermetically sealed cavity around the MEMS; and electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity through an electrical interconnect. ### Claim 2 (depends on 1) The method of claim 1, wherein bonding the first substrate and the second substrate to the actuator/sensor layer comprises one or more of fusion bonding, eutectic bonding, anodic bonding and glass frit bonding to form the hermetically sealed cavity around the MEMS. ### Claim 3 (depends on 2) The method of claim 2, wherein the electrical interconnect comprises a lateral contact structure in contact with the electrically conductive regions of the MEMS device extending from the hermetically sealed cavity between the actuator/sensor layer and the first or second substrate, and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises exposing a portion of the lateral contact structure. ### Claim 4 (depends on 3) The method of claim 3, wherein bonding the first substrate and the second substrate to the actuator/sensor layer further comprises hermetically sealing the lateral contact structure to the actuator/sensor layer and the first and second substrate. ### Claim 5 (depends on 3) The method of claim 3, wherein the lateral contact is a multilayer contact structure comprising one or more interleaved dielectric layers and conductive layers. ### Claim 6 (depends on 2) The method of claim 2, wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises forming a silicon via through either the first or second substrate to the electrically conductive regions of the MEMS device. ### Claim 7 (depends on 2) The method of claim 2, wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises forming a silicon via through either the first or second substrate to a lateral contact structure in contact with the electrically conductive regions of the MEMS device extending from the hermetically sealed cavity between the actuator/sensor layer and the first or second substrate. ### Claim 8 (depends on 2) The method of claim 2, wherein fusion bonding comprises forming fusion bonds between layers formed on the first substrate, the second substrate and the actuator/sensor layer and comprising one or more of silicon, silicon-dioxide or silicon-nitride. ### Claim 9 (depends on 1) The method of claim 1, further comprising dicing the bonded first substrate, the actuator/sensor layer and second substrate to form individual MEMS packaged with wafer level chip scale packaging (WLCSP). ### Claim 10 (depends on 9) The method of claim 9, further comprising wire bonding the pad to a complementary metal oxide semiconductor (CMOS) die and packaging individual MEMS and CMOS die in a multi-die package. ### Claim 11 (depends on 1) The method of claim 1, wherein at least one of the first or second substrates further includes a complementary metal oxide semiconductor (CMOS) integrated circuit (IC), and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises electrically connecting the electrically conductive regions of the MEMS device through the CMOS IC. ### Claim 12 A method comprising: forming a number of Micro-Electromechanical System (MEMS) devices including electrically conductive regions therein on a surface of a first substrate; forming a number of first open cavities in the surface of the first substrate underlying the number of MEMS devices; forming a number of second open cavities in a surface of a second substrate corresponding to the first open cavities; and aligning the first substrate to the second substrate so that at least one of the number of the first and second open cavities align with at least one of the number of MEMS devices; hermetically sealing the cavity around the MEMS device by bonding the first substrate to the second substrate; and electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity through an electrical interconnect. ### Claim 13 (depends on 12) The method of claim 12, wherein the electrical interconnect comprises a lateral contact structure in contact with the electrically conductive regions of the MEMS device extending from the hermetically sealed cavity between the first and second substrate, and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises exposing a portion of the lateral contact structure. ### Claim 14 (depends on 12) The method of claim 12, wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises forming a silicon via through either the first or second substrate to the electrically conductive regions of the MEMS device. ### Claim 15 (depends on 12) The method of claim 12, forming the number of first open cavities in the surface of the first substrate is performed concurrently with forming the number of MEMS devices using an etching process. ### Claim 16 (depends on 12) The method of claim 12, wherein at least one of the first or second substrates further includes a complementary metal oxide semiconductor (CMOS) integrated circuit (IC), and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises electrically connecting the electrically conductive regions of the MEMS device through the CMOS IC. ### Claim 17 A method comprising: etching a number of first open cavities in a surface of a first substrate to form a top cap (TCAP); forming an actuator/sensor layer including a number of Micro-Electromechanical System (MEMS) devices with electrically conductive regions therein; bonding the first substrate to the actuator/sensor layer so that at least one of the number of the first open cavities aligns with at least one of the number of MEMS devices; etching a number of second open cavities in a surface of a second substrate corresponding to the first open cavities to form a bottom cap (BCAP); bonding the second substrate to the actuator/sensor layer so that at least one of the number of the second open cavities align with at least one of the number of MEMS devices and at least one of the first open cavities to form a sealed cavity around the MEMS device; and electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity through an electrical interconnect, wherein at least one of the first or second substrates further includes a complementary metal oxide semiconductor (CMOS) integrated circuit (IC), and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises electrically connecting the electrically conductive regions of the MEMS device through the CMOS IC. ### Claim 18 (depends on 17) The method of claim 17, wherein bonding the first substrate and the second substrate to the actuator/sensor layer comprises one or more of fusion bonding, eutectic bonding, anodic bonding and glass frit bonding to form a hermetically sealed cavity around the MEMS. ### Claim 19 (depends on 18) The method of claim 18, wherein the electrical interconnect comprises a lateral contact structure in contact with the electrically conductive regions of the MEMS device extending from the hermetically sealed cavity between the actuator/sensor layer and the first or second substrate, and wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises exposing a portion of the lateral contact structure. ### Claim 20 (depends on 18) The method of claim 18, wherein electrically connecting the electrically conductive regions of the MEMS device to a pad outside of the sealed cavity comprises forming a silicon via through either the first or second substrate to the electrically conductive regions of the MEMS device. ### Claim 21 (depends on 17) The method of claim 17, wherein the actuator/sensor layer comprises single crystalline silicon, and further comprising thinning the actuator/sensor layer to a thickness of 60 um or less prior to bonding the second substrate to the actuator/sensor layer. ### Claim 22 (depends on 21) The method of claim 21, further comprising forming anti-collision extrusions on the actuator layer to prevent stiction and limit the actuator layer travel range.