Significance   Transparent hard brittle materials have been widely used in the fields of semiconductors and electronics due to their excellent mechanical properties, thermal stability, corrosion resistance, and optoelectronic properties. The traditional slicing method for transparent hard brittle materials has low efficiency and high material loss, which restricts the promotion and application of hard brittle materials. Diamond wire cutting is commonly used in the cutting of high-hardness and brittle materials. The existing substrate processing technology has slow cut speed, and there is a large loss of transparent and brittle materials and cutting lines. Every time a piece of transparent and brittle material is processed, a large amount of wire cutting loss will be caused by wire saw cutting, greatly increasing the cost of splitting transparent and brittle materials. The laser assisted separation technology, which leads to expensive separation processes, is a new method for slicing transparent hard brittle materials in recent years. It revolutionarily utilizes nonlinear optical effects to make laser pass through transparent hard brittle materials, causing a series of physical and chemical processes such as thermal damage and laser induced ionization inside the transparent hard brittle materials, forming a thin modified layer, and ultimately achieving the splitting of transparent hard brittle materials. Compared with traditional diamond wire cutting methods, it greatly improves the slicing efficiency and material utilization of hard and brittle materials. In the field of laser processing of hard and brittle materials, it has developed into a common focus of academic research and industrial applications.

  Progress  This article provides an in-depth analysis of the physical process of laser separation of transparent hard brittle materials and summarizes the key scientific issues in the process of laser separation, which are the nonlinear absorption of laser by transparent hard brittle materials, the evolution of the internal microstructure of transparent hard brittle materials under laser action, and the mechanism of the influence of laser field regulation on material modification. Combining special optical design, beam shaping, multi-factor coupling and stripping techniques and based on these scientific issues, this article reviews the research progress of laser separation of different types of transparent hard brittle materials in recent years. At present, materials used for laser separation include semiconductor materials such as SiC (Fig.8), Si, GaN (Fig.12), diamond (Fig.13), and ceramic materials such as sapphire, polycrystalline Al₂O₃, and zirconia. Laser separation technology has developed multiple splitting methods. For example, ultrafast laser dual pulse induced separate, ultrafast laser chemically assisted splitting, multiple laser composite splitting, etc. Multiple companies and research institutes at home and abroad are actively promoting the research and development of fully automated laser stripping equipment, with laser technology as the core for industrial and specialized manufacturing machines.

  Conclusions and Prospects  The physical process of vertical laser detachment is a typical interdisciplinary problem in the thermodynamics of laser materials. Laser splitting can almost completely avoid the cutting loss caused by conventional multi-wire cutting technology. Only the peeled lenses need to be ground and polished, so the loss of each transparent hard brittle material can be significantly reduced to below 100 microns, thereby increasing the production of transparent hard brittle materials. Despite significant breakthroughs and rapid development in experimental results, there is still a lack of in-depth theoretical and numerical simulation research on the process mechanism of laser separate technology. In the future, the vertical laser splitting technology for hard and brittle materials will develop towards ultra-thin material splitting with smaller material losses below 100 microns, low damage of modified layers, and process adaptability. In addition, laser splitting technology can also be applied to the development of transparent hard and brittle materials in areas such as thinning, polishing, and surface modification. This paper provides greater technical support for the rapid development of semiconductors and electronics.