Fabrication of laterally displaced porous silicon filters

Porous silicon superlattices have been used to manufacture laterally displa ced dielectric filters with different optical properties on one substrate. Two different fabrication processes for two-colour microfilter arrays are p resented. Both methods overcome the problem of non-uniform optical properti es of the well-known procedure where two filter stacks are grown one upon a nother, with subsequent partial removal of the upper filter by reactive ion etching. The novel methods give uniform optical properties of the two filt er areas, profiting from the main property of the formation process of poro us silicon: the formation of porous silicon occurs only at the porous silic on-substrate interface. (C) 2001 Elsevier Science B.V. All rights reserved.