Naoki Nishida

Evaluation of a next generation EB mask writer for hp 32nm lithography

Lithography technologies promising for the half pitch (HP) 32 nm generation include 193 nm immersion with water, extreme ultraviolet lithography (EUVL), and nano-imprint lithography (NIL). Among these, 193 nm immersion with water is considered a mainstream for hp 32 nm device fabrication in terms of performance and device production costs. Meanwhile, according to the International Technology Roadmap for Semiconductors (ITRS) 2009, the optical masks for hp 32 nm devices need to meet extremely strict requirements; for example, an image placement accuracy of 3.8 nm (2.7 nm for double patterning), and CD uniformities of 1.5 nm (isolated lines) and 2.4 nm (dense lines). To meet these accuracy requirements, we have developed JBX-3200MV, a variable shaped beam mask writer featuring an accelerating voltage of 50 kV and a current density of 70 A/cm2. For this new writer, we developed a new digital-to-analog converter (DAC) amplifier designed to reduce noises input to electron beam optics components such as the main and sub positioning deflectors and the beam shaping deflectors. The stage and exposure chambers were enhanced in rigidity to reduce mechanical noises. The position of the stage is measured by laser devices with a finer resolution of 0.15 nm, and the measured results are fed back to the beam position. In addition, data transfer speed and proximity correction speed were improved to handle larger data volumes. Our exposure test results demonstrate that the new lithography system, installed at the leading-edge mask production facility, achieved the hp 32 nm mask accuracies required by the ITRS 2009.

Advanced photomask repair technology for 65-nm lithography (1)

The 65nm photomasks have to meet tight specifications and improve the production yield due to high production cost. The 65nm optical lithography has two candidates, 157nm and 193nm, and we are developing two types of experimental photomask repair systems, FIB and EB, for the 65nm generation. We designed and developed FIB and EB beta systems. The platforms of beta systems consist of anti-vibration design to reduce outer disturbance for repair accuracy. Furthermore, we developed a new CPU control system, especially the new beam-scanning control system that makes it possible to control the beam position below nanometer order. These developments will suppress transmission loss and improve repair accuracy of the systems. We also adopt the 6-inch mask SMIF pod system and the CAD data linkage system that matches the EB mask data image with the SED image to search defects in photomasks with sophisticated patterns such as OPC patterns. We evaluate the EB repair process, and confirm that it generates carbon film, which has possibility to generate the same quality as that of FIB. Furthermore, we confirmed that EB and FIB repair systems were able to deposit carbon film and etch chrome, quartz, and MoSi. In this paper, we report the photomask defect repair experimental systems and the feasibility study on photomask defect repair for the 65nm generation.

Advanced photomask repair technology for 65nm lithography (4)

Yasutoshi Itou, Yoshiyuki Tanaka, Osamu Suga *Yasuhiko Sugiyama, *Ryoji Hagiwara, *Haruo Takahashi, *Osamu Takaoka, *Tomokazu Kozakai, *Osamu Matsuda, *Katsumi Suzuki, *Mamoru Okabe, *Syuichi Kikuchi, *Atsushi Uemoto, *Anto Yasaka, *Tatsuya Adachi, **Naoki Nishida Semiconductor Leading Edge Technologies, Inc. 16-1, Onogawa, Tsukuba-shi, Ibaraki, 305-8569, Japan *SII NanoTechnorogy Inc. 36-1 Takenoshita, Oyama-cho, Sunto-gun, Shizuoka, 410-1393, Japan **HOYA Co. 1375 Kawaguchi-cho, Hachioji-shi, Tokyo, 193-8525, Japan

Development of halftone phase-shift blank and mask fabrication for ArF lithography

The halftone phase-shift mask has been in practical use for i-line and KrF lithography. In ArF lithography, the HtPSM is also considered to be a promising resolution enhancement technique for its simple structure and fabrication process required. We in HOYA have attempted to expand the applicability of our MoSi-based HtPSM blank technology to ArF lithography, helping extend the life of the existing infrastructure for conventional HtPSM fabrication. We have completed tuning our new MoSi-based film for ArF application. The films optical properties, chemical durability and ArF laser irradiation durability meet industry requirements; and it is compatible with conventional mask-making process and repair techniques for the KrF HtPSM.

Correlation of inspection methods in characterizing nanomachined photomask repairs

Nanomachining has become a mainstream process for repairing photomasks. The advantages of nanomachining versus other repair techniques are improved edge placement, reliable depth control, and minimized substrate damage. This technique can be applied to any defect that requires a subtractive repair process. The process can be equally well applied to defects of any material including unknown materials. This paper evaluates the correlation of different inspection methods in characterizing nanomachined photomask repairs. The repairs were made using an nm650 mask repair tool manufactured by RAVE LLC. The repairs were inspected using a 248nm Aerial Image Measurement System (AIMS) and the Atomic Force Microscope (AFM) image produced by the nanomachining tool itself. These repairs were performed on 248nm MoSi photomasks. Results were compared to measurements by SEM and optical edge placement measurement techniques.

Development of focused ion-beam repair for opaque defects on MoSi-based attenuated phase-shift mask

Focused-ion beam (FIB) repair technique is one of the important technologies for quality and productivity of attenuated phase shift mask (HT-PSM),especially for KrF lithography. Mainly, accurate and low damage technique are necessary for HT-PSM repair. Such requirements are satisfied with the improvement of gas-assisted etching (GAE) technique for FIB. New SIR-3000 made by Seiko Instruments has been developed for applying MoSi material etching. Using GAE technique, the transmittance evaluated from AIMS at repaired area was more than 99% (i-line), and 96 - 97% (KrF) without post process (Qz reference: 100%). The results indicate the focused-ion beam repair is applicable without post process to MoSi-based HT-PSM for KrF lithography. This paper report the characterization results of opaque defect repair on MoSi-based HT-PSM using new SIR-3000.

Development of MoSi-based halftone phase-shift blank and mask fabrication for ArF lithography (Photomask Japan 2000 Best Presentation Award)

The halftone phase-shift mask (HtPSM) has been in practical use for i-line and KrF lithography. In ArF lithography, the HtPSM is also considered to be a promising resolution enhancement technique for its simple structure and fabrication process required. We in HOYA have attempted to expand the applicability of our MoSi-based HtPSM blank technology to ArF lithography, helping extend the life of the existing infrastructure for conventional HtPSM fabrication. We have completed tuning our new MoSi-based film for ArF application. The film’s optical properties, chemical durability and ArF laser irradiation durability meet industry requirements; and it is compatible with conventional mask-making processes and repair techniques for the KrF HtPSM.