Continued momentum in the development of EUV photolithography toward high volume manufacturing has driven the evolution of increased photoresist purity requirements. Further scaling will intensify the challenge to improve inline yield and reliability performance. The composition of EUV photoresist materials requires careful compositional balance and stability to ensure expected lithographic performance. It is therefore critical to understand and assess interactions between photomaterials and the many touchpoints along the entire value chain to maintain the purity and integrity of these materials. <p> </p>Filtration technology is an important part of maintaining a material’s purity. When choosing a filter, there are many factors to consider, starting with the membrane material. For instance, nylon filters effectively remove polar polymers through an adsorption mechanism. Particulate contaminants are often removed by size-exclusion, mostly commonly observed with certain UPE (ultra-high molecular weight polyethylene) membranes. As lithography materials change and the smallest defects become even more challenging to detect, filtration technology innovation, such as the development of Oktolex<sup>TM</sup>, is needed to meet the most stringent defect targets. In this paper, a tailored filter is introduced to enhance filtration performance and address specific defect sources in EUV photoresists. Results and possible mechanisms of the defect reduction will be discussed.
ArF lithography is the primary technique used in leading edge semiconductor fabrication. However, as lithographers attempt to create manufacturable processes for N7 and future nodes, they are challenged to achieve improvements in cost of ownership and productivity. One means to reduce cost of ownership is to reduce photolithography layers, which can be achieved with EUV lithography. Chemical manufacturers are struggling to solve stochastic issues that evolve with the use of EUV lithography, as well as develop the many complementary materials required to enable the technology. Conventional filters such as Nylon and UPE (ultra-high molecular weight polyethylene) have been used in manufacture of photochemicals and new filtration technologies must be developed to innovate along with chemical suppliers. <p> </p>Entegris has recently developed several innovative membranes: a next generation UPE and Oktolex<sup>TM</sup>. The next generation UPE overcomes the trade-off between flow rate and pore size, while also being compatible with a range of chemistries. Oktolex<sup>TM</sup> selectively removes defects based on tailored membrane modification technology, further addressing defect sources that come from newly formulated chemistries. <p> </p>In this paper, these innovative technologies are introduced to address the challenges of advanced photoresist defectivity by enhancing filtration performance. Results and possible mechanisms of defect reduction will be discussed.