Methods for embedding controlled-cavity MEMS package in integration board

• US 8,866,237 B2
• Filed: 02/27/2012
• Issued: 10/21/2014
• Est. Priority Date: 02/27/2012
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Manack, Christopher D., Stepniak, Frank, Koduri, Sreenivasan K.
• Primary Examiner(s): Smith, Zandra
• Assistant Examiner(s): TYNES JR., LAWRENCE C
• Application Number:
  US13/405,513
• Publication Number:
  US 20130221455A1
• Time in Patent Office: 967 Days
• Field of Search: 257/416
• US Class Current: 257/416
• CPC Class Codes: B81B 2201/0207 Bolometers
• CPC Class Codes: B81B 7/0067 for controlling the passage of optical signals through the package
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: G01J 5/045 Sealings; Vacuum enclosures; Encapsulated packages; Wafer bonding structures; Getter arrangements getter arrangements per se H01L23/26 and H01L21/3221
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: H01L 2224/04105 Bonding areas formed on an encapsulation of the semiconductor or solid-state body, e.g. bonding areas on chip-scale packages
• CPC Class Codes: H01L 2224/12105 Bump connectors formed on an encapsulation of the semiconductor or solid-state body, e.g. bumps on chip-scale packages
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/24245 the item being metallic
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/82 by forming build-up interconnects at chip-level, e.g. for high density interconnects [HDI]
• CPC Class Codes: H01L 2224/82039 using a laser
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/92144 the second connecting process involving a build-up interconnect
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 24/24 of an individual high density interconnect connector
• CPC Class Codes: H01L 24/82 by forming build-up interconnects at chip-level, e.g. for high density interconnects [HDI] interconnection structure between a plurality of semiconductor chips H01L23/5389
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/10271 : Silicon-germanium [SiGe]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/1433 : Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/1434 : Memory
• CPC Class Codes: H01L 2924/1461 : MEMS

Abstract

An embedded micro-electro-mechanical system (MEMS) (100) comprising a semiconductor chip (101) embedded in an insulating board (120), the chip having a cavity (102) including a radiation sensor MEMS (105), the opening (104) of the cavity at the chip surface covered by a plate (110) transmissive to the radiation (150) sensed by the MEMS. The plate surface remote from the cavity having a bare central area, to be exposed to the radiation sensed by the MEMS in the cavity, and a peripheral area covered by a metal film (111) touching the plate surface and a layer (112) of adhesive stacked on the metal film.

Claims

1. An embedded micro-electro-mechanical system (MEMS) comprising:

a semiconductor chip embedded in an insulating board, the chip having a cavity including a radiation sensor MEMS, the opening of the cavity at the chip surface covered by a plate transmissive to the radiation sensed by the MEMS;

the plate surface remote from the cavity having a bare central area, to be exposed to the radiation sensed by the MEMS in the cavity, and a peripheral area covered by a metal film touching the plate surface and a layer of adhesive stacked on the metal film.

2. The MEMS of claim 1 further including, on the peripheral plate surface, a conductive foil touching the adhesive layer on the metal film.

3. The MEMS of claim 1 wherein the radiation to be sensed by the MEMS is selected from a group including electro-magnetic radiation, such as visible or infrared light, acoustic radiation, such as sound, and chemical radiation, such as gases.

4. The MEMS of claim 1 wherein the cover plate is made of a cured photoresist material having a thickness of about 15 μ

m.

5. The MEMS of claim 1 wherein the protective metal film includes a titanium-tungsten layer of about 0.15 μ

m thickness on the cover plate and a copper layer of about 0.20 μ

m thickness on the titanium-tungsten layer.

6. A method for fabricating a micro-electro-mechanical system (MEMS), comprising the steps of:

providing a semiconductor chip having a cavity including a radiation sensor MEMS, the opening of the cavity at the chip surface covered by a plate transmissive to the radiation sensed by the MEMS; and

placing a patterned metal film across the plate surface remote from the cavity.

7. The method of claim 6 wherein the cover plate is made of a cured photoresist material having a thickness of about 15 μ

m.

8. The method of claim 6 wherein the protective metal film includes a titanium-tungsten layer of about 0.15 μ

m thickness on the cover plate and a copper layer of about 0.20 μ

m thickness on the titanium-tungsten layer.

9. A method for fabricating an embedded micro-electro-mechanical system (MEMS), comprising the steps of:

providing a chip having a radiation-sensing MEMS in a cavity covered by a plate having a patterned metal film on the plate surface remote from the cavity;

attaching the chip surface with the metal film onto a patterned conductive foil covered by a layer of adhesive;

embedding the non-attached chip body in an insulating board; and

removing from the cover plate sequentially portions of the conductive foil, then of the adhesive layer, and then of the metal film, thereby exposing the plate to the radiation to be sensed by the MEMS in the cavity.

10. The method of claim 9 wherein the step of removing portions of the conductive foil includes a chemical etching technique.

11. The method of claim 9 wherein the step of removing portions of the adhesive layer includes a laser technique.

12. The method of claim 9 wherein the step of removing portions of the metal film includes another chemical etching technique.

13. The method of claim 9 wherein the chip surface further includes chip terminals connected to the MEMS.

14. The method of claim 9 further including the step of connecting the chip terminals to the patterned conductive foil.

15. The method of claim 9 wherein the cover plate is made of a cured photoresist material having a thickness of about 15 μ

m.

16. The method of claim 9 wherein the protective metal film includes a titanium-tungsten layer of about 0.15 μ

m thickness on the cover plate and a copper layer of about 0.20 μ

m thickness on the titanium-tungsten layer.