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Patent Issued for MEMS Sensing Device and Method for the Same

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Wang, Chuan-Wei (Hsin-Chu, TW); Tsai, Ming-Han (Hsin-Chu, TW), filed on July 22, 2013, was published online on July 8, 2014.

The patent's assignee for patent number 8772885 is PixArt Imaging Incorporation, R.O.C. (Hain-Chu, TW).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a Micro-Electro-Mechanical System (MEMS) sensing device and a method for making the MEMS sensing device, in particular to such MEMS sensing device and method wherein a packaging process is integrated in the manufacturing process for making the device.

"MEMS devices are miniature devices integrating electrical and mechanical functions, and often made by semiconductor processes. Typical commercial products of such devices include pressure sensors, accelerators, gyroscopes, optical telecom devices, digital light processors (DLPs), inkjet heads, RF sensing devices for wireless network and so on. They are applied to vehicle tire pressure gauges, optical telecom networks, projectors, sensing networks, digital microphones, clock oscillators, interactive gamers and several other kinds of products. The MEMS devices also play major roles even in many developed researches of new generation memory techniques, biochips, display techniques, and emerging energies.

"Traditional MEMS chips require complicated assembling (or packaging) processes, such as QFN (Quad Flat No leads) or LGA (Land Grid Array), so that they can be applied to and combined in the foregoing products. FIG. 1 shows a cross-sectional diagram of a prior art pressure sensor. As shown in FIG. 1, the pressure sensor 10 comprises a MEMS chip 11, a packaging housing 13, an insulating adhesive 15, a plurality of bonding wires 17 and a QFN leadframe 19. The MEMS chip 11 is mounted on the die pad 193 of the QFN leadframe 19, and is electrically connected to the contacts 191 of the QFN leadframe 19 through the bonding wires 17. The packaging housing 13 covers the MEMS chip 11, and is bonded with the QFN leadframe 19. The through hole 131 of the packaging housing 13 allows external air outside the pressure sensor 10 to directly pressure the MEMS chip 11, so that the external air pressure can be measured. However, manufacturing such QFN or LGA type MEMS devices require complicated packaging processes and multiple materials some of which are not commonly used in a typical CMOS semiconductor process. Thus, the cost is undesirably high.

"In view of above disadvantages, the present invention provides a method for making a MEMS sensing device that integrates a wafer level packaging process after a CMOS process, so that the packaging process is simplified and the manufacturing cost is also reduced.

"For reference, the following patents disclose contents related to the present application: U.S. Pat. Nos. 6,012,336, 6,536,281, 6,928,879, 7,121,146, 6,743,654, and 7,135,749."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "An objective of the present invention is to provide a method for making a MEMS sensing device into which a packaging process is integrated. Another objective of the present invention is to provide a MEMS sensing device.

"To achieve the foregoing objectives, in one aspect, the present invention provides a MEMS sensing device, comprising: a substrate having a first surface and a second surface opposite the first surface; a MEMS device region on the first surface of the substrate, the MEMS device region including a chamber; a film overlaid on the MEMS device region to seal the chamber as a sealed space; an adhesive layer; a cover mounted on the MEMS device region and adhered by the adhesive layer; and a plurality of leads electrically connected to the MEMS device region and extending to the second surface.

"In one embodiment, the MEMS sensing device further comprises at least one opening on the cover or the adhesive layer.

"In one embodiment, the MEMS device region includes a variable capacitor whose capacitance is changeable according to air pressure acting on the film.

"In one embodiment, the plurality of leads are a plurality of TSVs (Through Silicon Vias) through the substrate.

"In one embodiment, the leads are a plurality of T contacts.

"In one embodiment, the opening allows external air outside the MEMS sensing device to pressure the film.

"In another aspect, the present invention provides a method for making a MEMS sensing device, comprising: proving a substrate, wherein the substrate includes a first surface and a second surface opposite the first surface; forming a multilayer structure including a plurality of metal layers and an insulating region on the first surface of the substrate; removing a portion of the insulating region to form a chamber; providing a mask layer on the multilayer structure to form a MEMS device region; overlaying a film on the mask layer to seal the chamber as a sealed space; adhering a cover on the MEMS device region by an adhesive layer; forming a plurality of leads on the substrate, wherein the leads are connected to the MEMS device region and extend to the second surface; and forming at least one opening on the cover.

"In one embodiment, the leads are a plurality of TSVs through the substrate.

"In one embodiment, the leads are a plurality of T contacts.

"In one embodiment, the opening allows external air outside the MEMS sensing device to pressure the film.

"In another aspect, the present invention provides a method for making a MEMS sensing device, comprising: proving a substrate, wherein the substrate includes a first surface and a second surface opposite the first surface; forming a multilayer structure including a plurality of metal layers and an insulating region on the first surface of the substrate; forming a mask layer on the multilayer structure; removing a portion of the insulating region to form a chamber and make the multilayer structure become a MEMS device region; overlaying a film on the mask layer to seal the chamber as a sealed space; adhering a cover on the MEMS device region by an adhesive layer, wherein the adhesive layer has at least one opening; and forming a plurality of leads on the substrate, wherein the leads are connected to the MEMS device region and extend to the second surface.

"In one embodiment, the leads are a plurality of TSVs through the substrate.

"In one embodiment, the leads are a plurality of T contacts.

"In one embodiment, the opening allows external air outside the MEMS sensing device to pressure the film.

"The objectives, technical details, features, and effects of the present invention will be better understood with regard to the detailed description of the embodiments below, with reference to the drawings."

For additional information on this patent, see: Wang, Chuan-Wei; Tsai, Ming-Han. MEMS Sensing Device and Method for the Same. U.S. Patent Number 8772885, filed July 22, 2013, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8772885.PN.&OS=PN/8772885RS=PN/8772885

Keywords for this news article include: Electronics, Legal Issues, Semiconductor, PixArt Imaging Incorporation R.O.C..

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Source: Electronics Newsweekly


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