Takehiko Iwanaga

Defectivity and particle reduction for mask life extension, and imprint mask replication for high-volume semiconductor manufacturing

Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Jet and Flash* Imprint Lithography (J-FIL*) involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. Criteria specific to any lithographic process for the semiconductor industry include overlay, throughput and defectivity. The purpose of this paper is to describe the technology advancements made in the reduction of particle adders in an imprint tool and introduce the new mask replication tool that will enable the fabrication of replica masks with added residual image placement errors suitable for memory devices with half pitches smaller than 15nm. Hard particles on a wafer or mask create the possibility of creating a permanent defect on the mask that can impact device yield and mask life. By using material methods to reduce particle shedding and by introducing an air curtain system, test stand results demonstrate the potential for extending mask life to better than 1000 wafers. Additionally, a new replication tool, the FPA-1100 NR2 is introduced. Mask chuck flatness simulation results were also performed and demonstrate that residual image placement errors can be reduced to as little as 1nm.

Immersion exposure tool for 45-nm HP mass production

Canon has renewed its platform of exposure tools. The new platform, the FPA-7000, is designed to cover multiple generations. The lens performance of the FPA-7000AS5 achieves less than 6m&lgr;, while that of the AS7 is estimated to be less than 4m&lgr;. The illumination performance meets the target required for the 45nm node. The in-situ aberration monitor, called iPMI, attains the measurement repeatability of 1.45m&lgr;. Focus and overlay units have improved process robustness. A solution tool for optimization is introduced to be connected with the FPA-7000. Moreover, latest studies of immersion, such as nozzle pressure, temperature control and defect inspection result are reported, and we also discuss the possibility of high-refractive-index immersion.

Performance of a nanoimprint mask replication system

Nanoimprint lithography manufacturing equipment utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. Additionally, as this technology does not require an array of widediameter lenses and the expensive light sources necessary for advanced photolithography equipment, NIL equipment achieves a simpler, more compact design, allowing for multiple units to be clustered together for increased productivity. In this paper, we review the progress and status of the FPA-1100NR2 mask replication system and also discuss the methods used on wafer imprint systems to extend the life of a replica mask. Criteria that are crucial to the success of a replication platform include image placement (IP) accuracy and critical dimension uniformity (CDU). Data is presented on both of these subjects. With respect to image placement, an IP accuracy (after removing correctables) of 0.8nm in X, 1.0nm in Y has been demonstrated. Particle adders were studied by cycling the tool for more than 16000 times and measuring particle adders. Additionally, new methods, including on-tool wafer inspection and in-situ mask cleaning are being studied to further extend the replica mask life.