Three-dimensional integration circuits (3D ICs) have become an important direction of integrated circuits, which brings in a higher integration level, higher power density, and shorter wire length. However, the heat management challenge becomes one of the key limitations for the development of 3D integration which needs desperate solutions. To address this challenge, the researchers conducted an in-depth investigation into heat transfer technologies within key structures of 3D ICs. This paper aims to review the literature on thermal management technologies, with a particular emphasis on advancements in three critical areas: thermal interface materials (TIM), through-silicon vias (TSV), and heat sink designs. Continuous research and innovation in TIM, TSV, and heat sink structures have provided diverse approaches and technical solutions for addressing thermal management issues in 3D ICs. It is expected that this review article can help researchers in academia and industry to understand the state-of-the-art of heat transfer in 3D ICs and provide better research ideas.

In this paper, the effect of Fe in the buffer layer on laser lift-off (LLO) GaN high electron mobility transistor (HEMT) was studied. AlGaN/GaN HEMTs grown on Fe-doped and unintentionally doped buffer layers were separated from sapphire substrates using the 248 nm KrF excimer laser lift-off system. We analyzed the variations of crystal characteristic, two-dimensional electron gas (2DEG) characteristic and strain state of AlGaN/GaN HEMT films before and after LLO by X-ray diffraction (XRD), Hall and Raman methods. Distribution of Fe element in the GaN buffer layer was performed by secondary ion mass spectroscopy (SIMS). The results illustrate that a peak Fe concentration of 9.56×10¹⁸cm^-3 appears at the interface. Moreover, the crystal quality and 2DEG characteristics of the Fe-doped GaN film obviously degenerated with the formation of micro-cracks under the threshold laser separation energy density (Es). In this case, the threshold laser damage energy density (ED) was used to measure the anti-laser damage ability of GaN in LLO. The analysis considers that additional laser absorption centers, induced by Fe impurity energy level, coupled with great residual stress up to 1.0763 GPa in Fe-doped GaN, reduced the threshold laser damage energy density (ED).