Microelectronic device plays an important role in the information age, and integrated circuit is one of the most important components of microelectronic device. Moreover, lithography is a key technology for the production of high precision integrated circuits, which determines the performance of the final product. Lithography is the manufacture process of integrated circuits, which uses optical-chemical reactions, chemical or physical etching methods to transfer the circuit graphics to the single crystal surface or medium layer to form functional graphics. The development trend of microelectronic device is towards smaller, faster and higher density, while the traditional "top-down" methods, such as optical etching, have been difficult to meet the needs. However, as a "bottom-up" method, molecular self-assembly technology can image on solid surfaces, which can break through the traditional limitations of preparing nano-devices.
Lithography plays an irreplaceable role in the production of semiconductor chips for integrated circuits. The fields where semiconductor chips and the lithography technology can be applied include new energy field, information and communication equipment field, 4C industry, smart grid field and the others.
As the process has been improved, lithography has developed many new techniques, including the following ones.
- Electron beam lithography: The wavelength of electron beam lithography depends on the electron energy, and as the electron energy increases, the wavelength that exposed becomes shorter. Therefore, electron beam lithography is not limited by the Rayleigh-limit and products with nanoscale resolution can be obtained. In 2014, a water-based electron beam lithography method was reported, which simplifies the etching process and has the advantage of environmental friendliness.
Figure 1. The process of water-based electron beam lithography method.
- Self-assembly anodized alumina template lithography: Compared with traditional lithography, the template prepared by this chemical method has the following advantages. First, nanopores with high aspect ratio can be obtained. Second, the mask has good thermochemical stability. Third, nanopore arrays can be regulated by simple electrochemical oxidation. Fourth, the size of mask can be expanded upward. Finally, the price is low.
Figure 2. The process of making self-assembly anodized alumina template.
- Nanoimprint lithography: According to the curing of corrosion inhibitors, nanoimprint lithography can be divided into thermal nanoimprint lithography (thermal NIL) and ultra-violet nanoimprint lithography (UV NIL). Based on the way of printing contact, nanoimprint lithography can be divided into plate-to-plate, roll-to-plat and roll-to-roll.
- The others: Except for the technologies mentioned above, lithography also includes microelectron light-emitting diode lithography, nanosphere lithography, laser direct writing lithography, etc.
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- Deyang, Ji, Tao, et al. Nanosphere Lithography for Sub-10-nm Nanogap Electrodes[J]. Advanced Electronic Materials, 2017.