The important position of lithography technology in the semiconductor industry ​

Human society is no stranger to "carving" and "marking". As a symbol of civilization, people in ancient times carved a totem of life in the cave. As a symbol of modern science, people today carve the structure of circuits on semiconductor wafers. People in ancient times used wood and stone. Today, people are smarter and need to be carved on a smaller scale. People use electricity and light. It is also a moment, and it becomes a circuit when it is carved on a semiconductor.

   Of course, it is not as simple as theoretical analysis. Lithography is just to carve out the structure of the transistor device on the semiconductor and the path connecting the transistors. To truly realize the circuit, a series of chip process methods such as doping, deposition, and packaging are also needed. But photolithography is the first step, and the minimum size that the entire chip process can achieve is determined by the photolithography process.

   Since the invention of the first transistor in 1947 , science and technology have been developing rapidly, paving the way for the invention of more advanced, more powerful, cost-effective and more energy-efficient products. Despite the tremendous progress, the problems of transistor heating and current leakage have always been the key obstacles to making smaller transistors and making Moore's Law last effective. There is no doubt that certain materials that have been used to make transistors for the past 40 years need to be replaced.

The world's first transistor

   Counting from the advent of the first transistor, the development of semiconductor technology has been more than half a century, and it still maintains a strong development trend. It continues to follow Moore 's law that the chip integration will double in 18 months, and the device size will be doubled every three years. The speed of development is reduced by 0.7 times. IC production with large size, fine line width, high precision, high efficiency, and low cost is bringing unprecedented challenges to semiconductor equipment.

   During the manufacturing process, integrated circuits have undergone multiple processes such as material preparation, masking, photolithography, cleaning, etching, dosing, and chemical mechanical polishing. Among them, photolithography is the most critical process, which determines the advanced level of the manufacturing process. With the development of integrated circuits from the micron level to the nanometer level, the wavelength of light used in lithography has also changed from the 436nm and 365nm wavelengths in the near ultraviolet ( NUV ) range to the 248nm and 193nm wavelengths in the deep ultraviolet ( DUV ) range . At present, most chip manufacturing processes use 248nm and 193nm lithography technology. At present, the research on EUV extreme ultraviolet lithography technology with a wavelength of 13.5nm is also advancing rapidly.

In 1997 , IBM developed chip copper interconnection technology

   With the improvement of chip integration, higher and higher requirements are put forward on photolithography technology. In the 1980s , it was generally believed that the limit resolution reached by optical lithography was 0.5 , but with the application and development of some new technologies, including light sources, imaging lenses, photoresists, step-scanning technologies, and The development of lithography resolution enhancement technology ( RET ) has pushed the lithography limit to below the current 0.1 . Although some people are full of doubts about the potential of optical lithography, its tenacious vitality continues to break through the so-called limit resolution, which is the mainstream lithography technology currently used.

A whole 300mm wafer and a 65nm process manufacturing transistor provided by Intel

   Lithography is one of the key technologies of integrated circuits. It is an important economic factor in the entire product manufacturing. The cost of lithography occupies 35 % of the entire manufacturing cost . Lithography is also an important reason that determines the development of integrated circuits in accordance with Moore's Law. If there is no advancement in lithography technology, it is impossible for integrated circuits to go from micron to deep sub-micron and then to the nano-era.