The semiconductor industry has evolved in accordance with the Moore's Law, progressing from microelectronics in the 1980s to nanoelectronics in the early 2000s, eventually venturing into atomic-scale quantum technology. High accuracy requirements, a significant hurdle to scalability, need innovative solutions for new technologies due to ultra-small allowable size deviations. Conventional plasma-based technologies with energetic particles in defect engineering, etching, doping, and materials deposition processes add another challenge in minimizing unwanted damage in atomic scale regions. Implementing multi laser beams will provide etchants, dopants, and depositing radicals to the surface via photochemical dissociation of chemical agents, followed by the direct laser beam illumination that promotes the etching, doping, and recrystallization in chemical and thermal processes. The proposed multi-laser beam assisted chemical processes can be applied to various atomically thin materials systems and quantum computing applications. 

Related Publications:

Y. Rho‡ and K. Lee‡ et al., 2022, Nature Electronics, 5, 505–510 

Y. Rho, et al., 2019, ACS Applied Materials & Interfaces, 11 (42), 39385-39393

Y. Rho‡ and H.Kim‡ et al, 2022, Advanced Materials Interfaces, 9 (23), 2200634

M. Eliceiri‡, Y. Rho‡, et al, 2023, Journal of Vacuum Science and Technology A , 41, 2, 022602

 To meet increasing demands for new high-speed devices, the industry is actively adopting 3D integration of heterogeneous materials and technologies that further increase the number of transistors per device by interconnecting multiple functional components in chip and wafer levels. To advance the device formfactor to a complex 3D structure and adopt a new electronic/ photonic/ mechanical circuit design, the 3D packaging technology requires a radical development of materials processing toolset in a repeatable, high-throughput and high-precision manner. My research group will develop a new 3D semiconductor packaging process based on multi-color 3D additive manufacturing, laser machining/sintering, and inkjet printing technologies. I will implement a large field of view (FOV) optics and multiphoton absorption process by femtosecond laser for an unprecedentedly high volumetric printing rate while keeping submicron feature resolution (<µm3). A metal-organic network and photopolymer resin will be developed to produce heterogeneous metal, ceramic, and polymer structures in a single vat by multi-color laser process. 

Related Publications:

M.Yassa‡ and Y. Rho‡ et al., TBD, Stay tuned!

 The critical and immediate problems in many optoelectronics, sensors, and electrochemical devices are optical, thermal, and chemical degradation, which critically depend on the intrinsic surface/bulk defects and interfaces. These degradation processes often manifest in dynamic, far-from-equilibrium energy and mass transport. Therefore, this research track is focused on developing and implementing in-operando wide-field multimodal characterization for data-driven prediction of materials and device failure. The device performance degradation can be predicted based on the obtained data sets without testing under prolonged external chemical, thermal, and optical stimulations (Figure 4b). This prediction can be used for decision making for selective defect repair and process optimization. The proposed in-operando wide-field diagnostics will offer a unique pathway to systematic investigation of dynamic physicochemical phenomena in operating devices, which will provide rich information for design and development of robust device platforms. 

Related Publications:

Y. Rho et al., 2023, Optics Letters, 48 (14), 3789-3792 

Y. Rho et al., 2024, Optics Express, 32 (15), 26632-26639

 A nanoscale second harmonic generation (SHG) microscopy apparatus has been developed based on scanning near-field optical microscopy (SNOM). This technique enables a probing of chemical corrosion of ZnO nanowires. The origin of the experimentally observed high near-field SHG enhancement by the gold-coated tip and the sample was described by a plasmonic enhanced nonlinear energy transfer. In addition, ultrafast temporal resolution can be added by integrating the scattering SNOM and femtosecond pump and probe techniques. Ultrafast carrier dynamics (~1ps) in silicon nanowires can be extracted from an ultrafast scattering signal decaying curve obtained in nanoscale lateral resolution (~30nm). Our study enables a nanoimaging of ultrafast dynamics of materials properties, which will find promising applications in the future design of a broad range of electronic, photonic, and optoelectronic devices. The nanoscale temperature, chemistry, and photoconversion efficiency of the device will be in-situ probed by employing scanning thermal microscopy (SThM), photo-induced force microscopy (PiFM), and near-field photocurrent microscopy (SNPM), respectively,  

Related Publications: 

Y. Rho‡ and S.Yoo‡ et al., 2023 Nano Letters, 23 (5), 1843-1849 

J. Li‡, R. Yang‡, Y. Rho*, 2023 Nano Letters, 23 (4), 1445–1450

 A Kirigami pattern in a suspended graphene monolayer can be generated by a femtosecond laser ablation and an electron beam patterning. The produced Kirigami engineered graphene membrane showed broadened bandwidths, reduced resonance frequency, and enhanced amplitude by releasing stress at the boundary. By taking the virtue of light weight and ultrahigh mechanical strength of graphene, this result presents a promising route to miniaturized wide-band energy transferrable mechanical transducers with enhanced operational parameter range and energy transfer efficiency.  

Related Publication: 

C. Dai‡, Y. Rho‡ et al., 2022, Nano Letters, 22 (13), 5301–5306