Design and fabrication of metal bolometers on high porosity silicon layers

Fabrication and characterisation of metal bolometers on p-type porous silicon (PS) layers are presented as an alternative to more complex micromachining processes for thermal insulation of sensors. A comparison of Nb strips deposited on layers of PS of varying thicknesses and porosities and on other substrates such as amorphous glass and crystalline silicon is described. Results of electrical characterisation, photoacoustic depth profiling and FEM thermal analysis are presented. Photoacoustic investigation on very high porosity layers (greater than or equal to 90%) gives promising indications on the thermal insulation efficiency of thin PS layers, which could be competitive with suspended structures for their low cost and number of fabrication steps. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.