Robust Hierarchical Architectures for Comprehensively Compliant Semiconductors

  • Adrian Cavazos Sepulveda

Student thesis: Doctoral Thesis


A novel hierarchical flexing and stretching strategy for rigid semiconducting substrates was devised. Architectures for comprehensively compliant semiconductors were created as a result. Si and GaN-on-Si have been segmented into both highly flexible and rigid segments. An advanced controlled cleavage technique has been integrated into the manufacturing process. The bending radius of the substrate has been decoupled from the substrate thickness thus allowing for higher mechanical stability, while achieving bending radii below 250 .m. Novel fabrication workflows have been created, one of which is completely compatible with CMOS fabrication techniques, while still being cost effective. Each of the rigid segments have been designed to carry in excess of its own weight. The reliability of the interconnecting springs was examined by rugged cyclic bending and twisting tests. Finite element simulations in COMSOL exhibited no stress for the rigid segments. For the first time a flexible and/or stretchable Si substrate has been integrated with pick and place tool technology. Additionally the platform serves as a More-than-Moore technology, by folding the monocrystalline substrate on top of itself, while routing power through the flexible segments. This More-than-Moore (MtM) technology has the advantages of System-in-Package (SiP) but does not have the additional costs. From this compliant approach a qubic 4D electronic platform was created. An aerially deployable electronic system was achieved by incorporating thermal paste into the qubic platform. Energy storage, sensing, and actuating were successfully tested on the system. Buried cavities for microfluidics were developed for on-chip chemical and biological processes. A platform was developed for µTF-SOFCs deposition. Cavities were interconnected subterraneously and columnar anodes were developed to enhance the fuel flow in the fuel cell electrode. The triple phase boundary (TPB) was enhanced by over an order of magnitude in comparison to standard processing techniques. A subsequent, microfluidic platform was developed for biological applications. The wettability of the platform gave good results for water, as well as for neurobasal media buffer. Tests indicate that neurons can grow directly on the platform.
Date of AwardAug 10 2018
Original languageEnglish (US)
Awarding Institution
  • Physical Sciences and Engineering
SupervisorMuhammad Mustafa Hussain (Supervisor)


  • Flexible Electronics
  • Compliant Semiconductors
  • Robust Semiconductors
  • Microfluidic Platform
  • CMOS Compatible

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