By Innofocus Photonics Technology Pty Ltd
First of all, the 3D laser nanofabrication technology based on two-photon absorption mechanism can be understood as two-photon lithography in specific application areas (only in the case of using photoresist and in the etching process using a patterned photoresist as a mask). Although it is one of its functions, in general, 3D laser nanofabrication is not used as a photolithography technique. This is because one of the important advantages of 3D laser nanofabrication is the processing of 3D structures, which are generally used as stand-alone functional devices and not as etching masks, because etching techniques cannot transfer 3D structures. Two-photon absorption based processing mechanism has various advantages, one of which is that the material to be processed can be etched directly, so that patterning and etching can be done in one step, no additional etching steps are needed, saving processing steps, time and cost. Using 3D laser nanofabrication technology to process large-area devices first requires a large-area displacement stage and its travel would determine the size of the final device that can be processed. The current air-bearing-based large-area displacement stage can achieve a processing range of 1m x 1m, which can fully meet the needs of large-area processing. However, this is only a prerequisite, and having a large-area displacement station does not guarantee the processing of large-area, high-quality optical components, especially those with nanometer-level precision. There are two major problems that need to be solved: 1. Precise guarantee of the relative position of the laser focal spot to the sample. In large-area processing, the laser focus will deviate from the designed processing position during the large-area movement even if there is only a very small tilt angle (<0.1°) of the placement of the material to be processed, and precise processing cannot be achieved. However, a 0.1° tilt is basically unavoidable. It can be caused by the uneven thickness of the material being processed. The error caused by this tilt will significantly affect the quality of processing. Therefore, even if the displacement station is able to fulfil large-area movement, it is likely that only a small area resulted can meet the requirements of use. Therefore, real-time tracking of the sample surface to determine the processing position is especially important in large-area processing. The surface tracing function of Innofocus's nanofabrication system is a valuable invention that ensures accurate processing position throughout the whole processing area, enabling large-area processing of micro and nano optical components. 2. During high-resolution nanoscale processing achieved by 3D laser nanofabrication, nanoscale lines, points or grids will fill the required processing area. As a result, during the actual fabrication process, the displacement station would need to travel a really long distance (despite meter-level structure, the processing path would be up to 1012 meters, which is an enormous number). Even if the displacement station can travel at high speed (0.5 m / s), the entire fabrication process would take significant amounts of time, which has become a bottleneck in the current 3D laser nanofabrication technology that limits the yield. Therefore, the availability of multi-focus and making full use of laser energy, is a key factor of expanding the application area of 3D laser nanofabrication technology. Innofocus's unique multi-focus parallel fabrication function, which divides the laser energy into hundreds or thousands of focal points for parallel processing, in accordance with the desired processing target, increases the productivity of 3D laser nanofabrication technology by hundreds or thousands of times and achieves a breakthrough in large-area processing from the principle.
