CASSIC - Method of manufacturing a silicon carbide micromechanical structures with cavities

BACKGROUND

Sensors are frequently used in hostile environments (high temperatures or pressures, extreme chemical conditions). For such applications, resistant materials such as silicon carbide (SiC) are suitable candidates. However, due to its chemical inertness towards most chemical agents, conventional MEMS fabrication processes are difficult to apply to silicon carbide.

CASSIC offers a simple and effective method to elaborate SiC membranes on SiC substrates that can be the beginning for original SiC-based MEMS development.

HOW IT WORKS

The method to produce SiC micromechanical structures is a 3 steps process:

1.A carbonization step initiates the elimination of the silicon discrete structure,
2.A step of deposition of a second silicon carbide layer,
3.A step of annealing; where the discrete silicon structure is entirely eliminated.

KEY BENEFITS

•No etchant requiered to obtain Micromechanical structures with cavities
•No etching holes in the SiC layer required
•CASSIC enables the formation of hermetically sealed cavities
•Without sticking problem
•Whatever the crystal orientation of the silicon layer
•Self-sealed SiC membranes with perfectly controlled geometry and size
•The lateral size of the consumed silicon may vary from few nanometers to a few hundred micrometers: By adjusting the annealing duration

DEVELOPMENT STATUS

pre-industrial prototype

APPLICATIONS

Sensors for non-destructive testing in harsh environments