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.

Description

PRIORITY CLAIM[0001]The present application is a non-provisional application claiming the benefit of U.S. Provisional Application No. 62 / 464,814 filed on Feb. 28, 2017 by Francis J. Kub et al., entitled “SILICON CARBICE STRUCTURE, DEVICE, AND METHOD,” the entire contents of which is incorporated herein by reference.BACKGROUND OF THE INVENTIONField of the Invention[0002]The present invention relates to a structure and method of fabricating thick beam silicon carbide MEMS structure with low capacitance and good thermal expansion match.Description of the Prior Art[0003]3C-SiC is often used for microelectromechanical (MEMS) device structures. 3C-SiC material layers grown on silicon substrate typically have high residual stress, high dislocation density, and high surface roughness. The 3C-SiC material layers grown on a silicon substrate can be grown on silicon substrates with an (100) orientation surface or an (111) orientation surface. There is significant thermal expansion mismatch bet...

AI Technical Summary

Benefits of technology

The present invention provides a structure and method for making a suspended beam silicon carbide MEMS structure with low capacitance and good thermal expansion match. SiC material properties provide significant advantages for MEMS devices, such as lower noise, improved shock resistance, and better radiation resistance. The use of single-crystal hexagonal SiC for both the top N+ suspended beams, the anchor material structure, and the optional electrostatic sense electrode and the bottom handle first substrate ensures good thermal expansion match and low stresses. The use of semi-insulating SiC bottom first substrate reduces parasitic capacitance for electrostatic sense electrode and improves noise properties. The patent text describes several other features to implement improved SiC MEMS structures.

Problems solved by technology

3C-SiC material layers grown on silicon substrate typically have high residual stress, high dislocation density, and high surface roughness.

There is significant thermal expansion mismatch between the 3C-SiC epitaxial layer and a silicon substrate.

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