EUV chemically amplified resists (CAR) use a copolymer containing highly-polar poly hydroxy styrene (PHS), which is believed to easily aggregate and form gel-like polymers. These aggregates likely generate microbridge defects, an important yield detractor in leading-edge semiconductor manufacturing. Improvements in EUV photoresist quality and a reduction in on wafer defectivity require more selective removal for this specific contamination source. Earlier presentations have demonstrated the benefit of effective removal of gel-like polymers in ArF immersion photoresists using photochemical filters with functionalized membrane technology [1]. In this paper we introduce a new filter technology for gel-like polymer removal in EUV photoresists. This contamination control technology demonstrates improved efficiency for removing partial, highly polar chemicals and fine particles that cause gel-like polymers over previous filter generations. The filter also improves on wafer defect counts.
The progression of EUV (Extreme Ultra-Violet) lithography into high volume manufacturing is driving the evolution of increased photochemical purity requirements. Further scaling will intensify the challenge to improve inline yield, ensure supply chain integrity, and increase reliability. Si hardmask materials play an important role in pattern transfer, and therefore require strict compositional materials integrity and stability to ensure expected performance. It is therefore critical to assess interactions between Si hardmask materials and components in the chemical delivery system to ensure hardmask materials purity and overall integrity.
There has been an increasing demand on filtration technology to enhance material purity in semiconductor unit processes. Many efforts to improve filtration have focused on establishing retention ratings using various particulate contaminants. While this is an important parameter to understand particle removal, it is equally important to understand the fundamental interactions between photochemicals and filters. As materials change and the smallest defects become even more challenging to detect, new filter screening methodologies are needed to address the most stringent defect targets.
In this paper, a novel filter screening metrology is introduced to identify optimized filtration candidates for specific defect sources and improve defectivity in Si hardmask materials. Results and possible mechanisms of 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.
Entegris has recently developed several innovative membranes: a next generation UPE and OktolexTM. The next generation UPE overcomes the trade-off between flow rate and pore size, while also being compatible with a range of chemistries. OktolexTM selectively removes defects based on tailored membrane modification technology, further addressing defect sources that come from newly formulated chemistries.
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.
Defect source reduction in leading-edge iArF resists is a critical requirement to improve device performance and overall yield in lithography manufacturing processes. It is believed that some polar polymers can aggregate and be responsible for single or multiple micro-bridge defects. Further investigation into the formation of these defects is needed. We have previously presented the effective removal of gel-like polymers using nylon media [1]. However, as the industry is moving to smaller feature sizes, there is a need to further improve the defect removal efficiency. In this paper, a filter, comprised of a novel membrane called Azora with unique morphology and high flow performance is introduced. This new filter shows better on-wafer in an advanced ArF solution than conventional Nylon and UPE media. In addition, it shows improved stability during chemical storage. Results and possible retention mechanisms are discussed.
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