Wafer level packaging of mems devices

Abstract

A MEMS device is disclosed. The MEMS device comprises a MEMS substrate and a CMOS substrate having a front surface, a back surface and one or more metallization layers. The front surface being bonded to the MEMS substrate. The MEMS device includes one or more conductive features on the back surface of the CMOS substrate and electrical connections between the one or more metallization layers and the one or more conductive features.

1 . A MEMS device comprising:
 a MEMS substrate;   a CMOS substrate having a front surface, a back surface and one or more metallization layers; the front surface being bonded to the MEMS substrate;   one or more conductive features on the back surface of the CMOS substrate; and   electrical connections between the one or more metallization layers and the one or more conductive features.   
     
     
         2 . The MEMS device of  claim 1 , wherein the conductive features are solder balls. 
     
     
         3 . The MEMS device of  claim 1 , wherein the conductive features include a second conductive redistribution layer 
     
     
         4 . The MEMS device of  claim 3 , wherein a stress relief layer is formed beneath the second conductive redistribution layer 
     
     
         5 . The MEMS device of  claim 3 , wherein the conductive features are solder balls. 
     
     
         6 . The MEMS device of  claim 1 , wherein the electrical connections comprise
 one or more openings in the back-surface of the CMOS substrate exposing the one or more metallization layers;   a second insulating layer coating the sidewalls of the one or more openings in the back surface of the CMOS substrate; and   a conductive layer coating the insulating layer on the back surface of the CMOS substrate and on sidewalls of the one or more openings and providing physical and electrical contact to the one of more metallization layers.   
     
     
         7 . The MEMS device of  claim 1 , wherein the MEMS substrate comprises
 a handle wafer bonded to a patterned electrically conductive device layer with an insulating layer positioned between the two wafers   
     
     
         8 . The MEMS device of  claim 7  further comprising
 an opening penetrating completely through the handle wafer and the insulating layer, and exposing a device layer; and 
 a second conductive layer deposited onto the MEMS substrate such that the second conductive layer at least partially covers the surface of the MEMS substrate and the sidewalls of the opening include making physical contact to the device layer, wherein the conductive layer is electrically connected to the device layer. 
 
     
     
         9 . A MEMS device comprising:
 a MEMS substrate, wherein the MEMS substrate includes a handle wafer bonded to a patterned electrically conductive device layer with an insulating layer positioned between the two wafers;   an opening penetrating completely through the handle wafer and the insulating layer, and exposing the device layer; and   a conductive layer deposited onto the MEMS substrate such that the conductive layer at least partially covers the surface of the MEMS substrate and the sidewalls of the opening including making physical contact to the device layer thereby electrically connecting the conductive layer to the device layer.   
     
     
         10 . The MEMS device of  claim 9 , wherein the opening has sloped sidewalls. 
     
     
         11 . The MEMS device of  claim 10 , wherein a CMOS substrate is bonded to the MEMS substrate. 
     
     
         12 . The MEMS device of  claim 11 , wherein one or more openings in the back-side of the CMOS substrate exposing one or more metal interconnection layer. 
     
     
         13 . The MEMS device wafer of  claim 12 , wherein a second insulating layer coats the sloped sidewalls of the one or more openings in the back-side of the CMOS substrate. 
     
     
         14 . The MEMS device wafer of  claim 13 , wherein the conductive layer coats the insulating layer on the back-side of the CMOS substrate and on sidewalls of the one or more openings and provides physical and electrical contact to the one of more metal interconnection layers. 
     
     
         15 . The MEMS device wafer of  claim 9 , wherein one or more solder-balls are connected to the conductive layer. 
     
     
         16 . A MEMS device comprising:
 a MEMS substrate, wherein the MEMS substrate includes a top layer connected to an electrically conductive bottom layer;   an opening penetrating completely through the top layer, and exposing the bottom layer; and   a second electrically conductive layer deposited onto the MEMS substrate such that the second electrically conductive layer at least partially covers the surface and the sidewalls of the opening including making physical contact to the bottom layer, wherein the second electrically conductive layer is electrically connected to the bottom layer.   
     
     
         17 . The MEMS device of  claim 16 , wherein the opening has sloped sidewalls. 
     
     
         18 . The MEMS device of  claim 16 , wherein a CMOS substrate is bonded to the MEMS substrate. 
     
     
         19 . The MEMS device of  claim 18 , wherein one or more openings in the back-side of the CMOS substrate exposing one or more metal interconnection layer. 
     
     
         20 . The MEMS device of  claim 19 , wherein a third electrically conductive layer coats the insulating layer on the back-side of the CMOS substrate and on sidewalls of the one or more openings and provides physical and electrical contact to the one of more metal interconnection layers. 
     
     
         21 . The MEMS device wafer of  claim 20 , wherein one or more solder-balls are connected to the third conductive layer.