High throughput Jet and Flash Imprint Lithography for semiconductor memory applications

Abstract

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.There are two critical components to meeting throughput requirements for imprint lithography. Using a similar approach to what is already done for many deposition and etch processes, imprint stations can be clustered to enhance throughput. The FPA-1200NZ2C is a four station cluster system designed for high volume manufacturing.For a single station, throughput includes overhead, resist dispense, resist fill time (or spread time), exposure and separation. Resist exposure time and mask/wafer separation are well understood processing steps with typical durations on the order of 0.10 to 0.20 seconds. To achieve a total process throughput of 15 wafers per hour (wph) for a single station, it is necessary to complete the fluid fill step in 1.5 seconds. For a throughput of 20 wph, fill time must be reduced to only one second.There are several parameters that can impact resist filling. Key parameters include resist drop volume (smaller is better), system controls (which address drop spreading after jetting), Design for Imprint or DFI (to accelerate drop spreading) and material engineering (to promote wetting between the resist and underlying adhesion layer). In addition, it is mandatory to maintain fast filling, even for edge field imprinting. In this paper, we address the improvements made in all of these parameters to enable a 1.50 second filling process for a sub-20nm device like pattern and have demonstrated this capability for both full fields and edge fields. *Jet and Flash Imprint Lithography and J-FIL are trademarks of Molecular Imprints Inc.

Nanoimprint System for High Volume Semiconductor Manufacturing; Requirement for Resist Materials

“…The results are reported in Figure 11. The newest material enhanced drop spreading by a factor of three relative to the older material [12]. Fig.…”

“…In a recent experiment, resist drop diameter for a 1.0 pL drop was measured for three different substrate cases [12]: 1) Original resist on an adhesion layer 2) Modified resist on the adhesion layer material 3) A newer material combination designed to enhance drop spreading After resist jetting, the drops were exposed to UV light approximately 1 second to cure. The results are reported in Figure 11.…”

Promising Lithography Techniques for Next-Generation Logic Devices

“…By careful optimization of several parameters (resist drop volume, system controls, material engineering, design for imprint and system controls), fill time can be decreased. It has been reported that throughput per imprint station improved significantly to 15 wafers per hour with a 1.5 s fill time [60]. Now it is targeted at 80 wafers per hour on a four station.…”

Metrology and inspection required for next generation lithography

“…Among the wide variety of NIL technologies, jet and flash imprint (J-FIL) is the most suitable for IC fabrication for which high productivity and high yield are required. [16][17][18] Figure 1 shows the J-FIL process. Resist is selectively applied by an inkjet to an imprinting field whose size is almost the same as that of an exposure field of a conventional optical scanner (∼26 × 33 mm 2 ), and then a patterned mask (template) is directly contacted to the field with UV exposure.…”