Microfabrication of high-temperature silicon devices using wafer bonding and deep reactive ion etching

As part of an effort to develop a micro gas turbine engine capable of providing 10-50 W of electrical power in a package less than one cubic centimeter in volume, we report the fabrication and testing of the first hydrogen combustor micromachined from silicon. Measuring 0.066 cm ³ in volume, and complete with a fuel manifold and set of fuel injector holes, the fabrication of the device was largely enabled by the use of deep reactive ion etching (DRIE) and aligned silicon wafer bonding. The 150-W microcombustor has a power density in excess of 2000 MW/m³ and has been successfully demonstrated to provide turbine inlet temperatures up to 1800 K. After 15 h of experimental tests, the combustor maintained its mechanical integrity and did not exhibit any visible damage. Combined with the results of a materials oxidation study, these tests are used to demonstrate the satisfactory performance of silicon in the harsh oxidizing environment of a combustion chamber