CMOS fabrication of a light emitting diode based on silicon/porous siliconheterojunction

The fabrication in a standard CMOS line of a light emitting diode (LED) bas ed on silicon/porous silicon heterojunction is discussed. To fabricate the LED in a CMOS line, the porous silicon formation must br performed either a s the last or as an intermediate step. The former option requires a masking layer to protect the metallization level of the CMOS devices from the elec trochemical solution for the pc,rous silicon formation, whereas the latter forces an interruption in the process. Experimental tests on several materi als, routinely used in CMOS processes, show that no standard mask is suitab le Lo fully protect the CMOS Boom the electrochemical etch. Hence porous si licon formation should br performed as an intermediate step.