Yasushi Okubo

Evaluation of loading effect of NLD dry etching

Recently, loading effect is becoming a great issue in mask dry etching process. It is well known that the effect is affected by pattern density. To improve the issue, an advanced mask dry etching system using neutral loop discharge was applied for next generation mask fabrication, because the tool make is possible to get high plasma density and low gas pressure.

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.

Development of deep-UV MoSi-based embedded phase-shifting mask (EPSM) blanks

Embedded phase-shift mask (EPSM) has an advantage in comparison with several other phase-shifting mask approaches because of its simple structure and fabrication process. We tried to modify MoSi-based EPSM blanks by re-examining the material and by optimizing sputtering condition in order to produce more useful EPSM blanks for Deep UV lithography technology. New MoSi-based EPSM blanks for which Nitrogen gas is used as the reactive sputtering gas has been developed. And it has been confirmed that the New MoSi-based EPSM (MoSi-N) blanks are superior to HOYA previously developed one (MoSi-ON) in chemical durability, manufacturing stability and Dry Etching property.

A comprehensive reticle handling and storage approach for optimized fab yields

In the field, each customer uses their owned designed reticle case as for shipping, storage. To modify the case is so expensive that it is very difficult to improve, especially in time respect. At the blank suppliers, they ship their mask blanks packing into their owned designed multiple shipper, however the market needs single shipper with next generation blanks to prevent from particle and outgas of case material damage. At the mask shops, most of them use MP567 (Trade mark of Dainichi Shoji K.K.) single case which was designed about 15years ago to ship their products to their customers. It is not designed for robot handling, so contamination from manual handling makes reticle damaged. Adhesive tape is also required to seal it, so chemical contamination will be occurred on quartz glass, i.e. haze. At the IC fabs, scanner case such as Nikon, Canon and ASML case is the most common in their process. However these cases are not airtight, so they cannot be handled under class 10000 circumstances. RSP (Reticle SMIF Pod) has a capability of automatic transportation, however it is not airtight case. We develop new mask case named Universal Reticle Pod (URP) at affordable price, airtight and chemical tight so as to be used as shipping, storage and process case. We evaluate it as blanks shipping case, so we would like to report its results.

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.

Development of novel W/Si materials for the single-layered attenuated phase-shifting mask

A novel material system of metal W corpuscles dispersed in silicon dioxides layer (W/Si film) has been developed for the single-layered attenuated phase-shifting mask (SAttPSM) for i-line. The W/Si film has been proved to have a wide flexibility in designing the optical transmittance and the film thickness by changing the sputtering conditions such as the O2 ratio to the sputtering gas (O2 and Ar) flow rate and the RF power supplied. The W/Si shifter film are also found to have some electric conductivity, which again depends on the sputtering conditions, tough chemical durability against both hard acid and basic solutions, and sufficient adhesion to quartz substrate SAttPSM, fabricated with the W/Si film and having the thickness of 1575 angstroms and the transmittance of 6.3%, showed the phase-shifting angle of 177.9 at i-line wavelength. The depth of focus around 0.35 micrometers hole pattern was widened from 0.6 micrometers to 1.4 micrometers .