By Canon
Canon has achieved miniaturization at lower power consumption and lower cost with nanoimprint lithography (NIL), a new technology that is an alternative to conventional lithography technology. By enabling inexpensive production of patterns of 15nm or smaller, NIL is poised to revolutionize the semiconductor industry. Unlike conventional lithography technology that uses light to expose circuit patterns, NIL does not require a light source. Circuits are formed using a simple principle that involves transferring a circuit pattern mask (mold) onto the coated resist (resin) on the surface of the wafer (a thin silicone plate). To overcome a number of these issues, Canon began by working on technology to control the amount and positioning of the resin applied to the wafer surface. This technology precisely controls how much and where the resin is applied to prevent it from being squeezed out when the mask is pressed into the resin, while also ensuring the formation of a resin layer with a uniform thickness, regardless of the size or number of indentations on the mask being used. Next, Canon developed a nanometer-level control technology to prevent the deformation of the convex circuit patterns formed in the resin, making it possible to cleanly remove the mask from the wafer. For NIL equipment, it is necessary to align transferred patterns that are tens of nm (nm: nanometer = one billionth of a meter) in size with nanometer-level accuracy. To achieve high-accuracy measurement of positional deviations, Canon has developed a system that makes it possible to measure positional deviations between the mask and the wafer in real time (Fig. 1). By using optimal moiré patterns as well as proprietary optical technologies and control technologies developed in collaboration with U.S.-based Canon Nanotechnologies, Inc. (CNT), NIL equipment can measure and correct for positional deviations between the mask and the wafer with nanometer-level accuracy. Canon has developed a proprietary matching system that achieves alignment by using laser irradiation to thermally deform the wafer (Fig. 2). This system makes it possible to change the heat input pattern and freely deform the wafer by controlling an ultra-fine mirror group called a Digital Micromirror Device (DMD). Canon spent a long time studying the use of ultra-high-performance filters in order to eliminate particles and utilizing design technology enabling the smooth flow of air into NIL equipment despite its complexity and many moving parts (Fig. 4). Canon also employs particle-elimination units to deal with particles that manage to get into the equipment, and has developed technology including air curtains (Fig. 5) that are used to section off ultra-clean environments for the most important areas by dividing areas based on how clean they are. NIL is able to form complex two- and three-dimensional patterns in a single pass, power consumption can be reduced by about one-tenth compared to advanced logic exposure technology. In addition, the range of possibilities for semiconductors that can be manufactured using NIL is expanding to include DRAM which is memory for storing data, logic for processing data and controlling equipment, and even micro-optical elements in addition to semiconductors.
Semiconductor manufacturing relies on exposure, a process that transfers circuit patterns onto silicon wafers. As circuit miniaturization advances in response to demand for increased data-processing capacity, challenges associated with traditional optical lithography, such as high power consumption, are becoming increasingly pronounced. To address these issues, Canon developed Nanoimprint Lithography (NIL) as a next-generation technology. Following the launch of NIL-equipped systems in 2023, customers who have adopted this equipment have been making final adjustments in order to optimize mass production lines for semiconductor manufacturing. If we think of optical lithography as "projecting shadows with light," NIL is almost like "stamping." The most distinctive feature of NIL is a template, called a “mask,” engraved with circuit patterns and pressed directly onto the resin applied to the wafer. This allows complex structures to be formed all at once in a single step, eliminating the need for repetitive exposures which are required in conventional optical lithography. Also, because NIL doesn’t use a light source to form circuit patterns, it offers the significant advantage of reducing power consumption to approximately one-tenth that of conventional methods.
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