Double transfer of thin single crystalline processed layer can be very interesting for all technologies that require front and back side engineering of the silicon active film. With the increase of the electronical system complexity, this alternative technology can offer new opportunities to miniaturize the semiconductor devices. To fulfill such requirements, a recent alternative technology was developed at the CEA-LETI, based on the use of porous silicon substrates [1]. This new technology will be of a great interest for 3D integration, back-side imager but also MEMS or photovoltaics applications. This technology should now be validated at a larger scale, and we need to focus on all involved mechanisms such as the porous silicon layer rupture.
In a first place, the applicant should comprehend the specification of porous materials in thin film configuration, including elaboration steps and distinctive properties of transferred porous layers. Subsequently he/she may need to interact with Leti’s technological experts to determine process improvements to be implemented to reach pre-established specifications of desired prototypes. In order to evaluate and recommend appropriate materials and equipments, he/she may need to extensively focus on the behaviour of porous material under specific stress conditions such as chemical, thermal or mechanical solicitations. The purpose is to ensure compliance to Smart Cut or Smart stacking technologies that involve amongst others processes molecular bonding technology.
Later, the effort should be focused on the development of a specific technology to induce the mechanical separation inside the buried porous silicon layer. One line of approach would be to trigger the mechanical separation by ultrasound solicitation. Understanding the mechanisms of the splitting and characterising the resulting structures are part of the expected work to be completed in this project.
[1] A-S.Stragier et al., JECS,158 (5) H595-H599 (2011)