A process for producing a microelectronic device includes producing a first semiconductor substrate which includes a first layer and a second layer present between a first side and a second side of the substrate. First electronic components and an interconnecting part are produced on and above the second side. The substrate is then thinned by a first selective etch applied from the first side and stopping on the first layer followed by a second selective etch stopping on the second layer. A second substrate is attached over the interconnecting part. The electronic components may comprise optoelectronic devices which are illuminated through the second layer.