Silicon carbide structure, device, and method

Abstract

A structure and method of fabricating suspended beam silicon carbide MEMS structure with low capacitance and good thermal expansion match. A suspended material structure is attached to an anchor material structure that is direct wafer bonded to a substrate. The anchor material structure and the suspended material structure are formed from either a hexagonal single-crystal SiC material, and the anchor material structure is bonded to the substrate while the suspended material structure does not have to be attached to the substrate. The substrate may be a semi-insulating or insulating SiC substrate. The substrate may have an etched recess region on the substrate first surface to facilitate the formation of the movable suspended material structures. The substrate may have patterned electrical electrodes on the substrate first surface, within recesses etched into the substrate.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . A silicon carbide MEMS structure, comprising:
 one or more suspended material structures comprising hexagonal single-crystal SiC material, wherein the thickness of the one or more suspended material structures is greater than 1 micron and up to 500 microns;   one or more anchor material structures comprising hexagonal single-crystal SiC material; and   a substrate;   wherein the one or more suspended material structures are attached to the one or more anchor material structures; and   wherein the one or more anchor material structures are bonded to the substrate.   
     
     
         2 . The silicon carbide MEMS structure of  claim 1 , wherein the substrate is semi-insulating. 
     
     
         3 . The silicon carbide MEMS structure of  claim 1 , wherein the hexagonal single-crystal SiC material is a 4H or 6H SiC material. 
     
     
         4 . The silicon carbide MEMS structure of  claim 1 , wherein the substrate has an etched recess region. 
     
     
         5 . The silicon carbide MEMS structure of  claim 1 , wherein the substrate has patterned electrical electrodes. 
     
     
         6 . The silicon carbide MEMS structure of  claim 1 , wherein the one or more anchor material structures are bonded to the substrate by direct wafer bonding. 
     
     
         7 . The silicon carbide MEMS structure of  claim 1 , wherein the aggregate linear thermal expansion coefficient of the substrate has a value that is within about 10 percent of the thermal expansion coefficient on the SiC material used for the suspended material structure. 
     
     
         8 . The silicon carbide MEMS structure of  claim 1 , wherein the SiC used for the suspended material structure has a residual stress less than about 100 MPa. 
     
     
         9 . The silicon carbide MEMS structure of  claim 1 , wherein the substrate is a glass substrate. 
     
     
         10 . The silicon carbide MEMS structure of  claim 1 , wherein the one or more anchor material structures are bonded to the substrate by anodic bonding. 
     
     
         11 . A method of making a silicon carbide MEMS structure, comprising:
 bonding a hexagonal single-crystal SiC material to a substrate, wherein the thickness of the hexagonal single-crystal SiC material is greater than 1 micron and up to 500 microns; and   etching trenches entirely through the hexagonal single-crystal SiC material to form suspended material structures.   
     
     
         12 . The method of  claim 11 , further comprising etching a recess into a first surface of the substrate before bonding the hexagonal single-crystal SiC material. 
     
     
         13 . The method of  claim 11 , wherein the substrate is semi-insulating. 
     
     
         14 . The method of  claim 11 , wherein the substrate is a 4H or 6H SiC substrate. 
     
     
         15 . The method of  claim 11 , wherein the substrate has patterned electrical electrodes. 
     
     
         16 . The method of  claim 11 , wherein the one or more anchor material structures are bonded to the substrate by direct wafer bonding. 
     
     
         17 . The method of  claim 11 , wherein the substrate is a glass substrate. 
     
     
         18 . The method of  claim 11 , wherein the one or more anchor material structures are bonded to the substrate by anodic bonding.