No abstract

The challenges, mask manufacturing is faced with, are more and more dominating the semiconductor industry as the pattern sizes shrink. Today's mask patterns have reached sizes that are common in wafer manufacturing. Looking into the industry, we can see that some of the quality parameters -such as CD uniformity and defect control -are managed better in wafer than in mask manufacturing. Consequently, mask manufacturers have started to apply more wafer processing techniques to mask processes. Among others, develop process has a great impact on the quality of the mask manufacturing. This contribution describes how Tokyo Electron Limited (TEL) scanning (linear drive nozzle) developer processing (widely used in advanced wafer manufacturing) was adapted for mask development. Out of this technology transfer, a new alpha-type mask develop tool was launched at TEL and an evaluation of this tool was carried out at the Advanced Mask Technology Center (AMTC), Dresden, Germany. Target of this collaboration was to successfully transfer wafer processing technology to mask making. By this, valuable information was generated, that has been implemented into the production platform, which is commercialized since first half of 2004.

A new photomask develop tool designed by Tokyo Electron Limited (TEL) with wafer puddle technology was evaluated at the Advanced Mask Technology Center (AMTC) in Dresden, Germany. Parameters selected for this evaluation were resist dark loss uniformity, critical dimension (CD) uniformity, loading, linearity, resist cross sectional images, and defects using chemically amplified resists (CARs) exposed with DUV (λ=257nm) and 50KeV e-beam pattern generators. Implementing wafer puddle technology to photomask developing was not a simple, straightforward process. Standard CAR puddle recipes for wafer developing were inadequate to match CDU requirements for photomasks at the 130nm technology node using DUV exposure. While the results were disappointing, the TEL alpha develop tool cannot be held entirely responsible. Other, non-develop tool related factors such as resist, substrate, coating bake temperature and time, lithography tool, and post exposure bake temperature and time, all contributed to the final post develop results. Indeed, other CAR/substrate combinations exposed at 50keV e-beam and processed on the TEL alpha develop tool were markedly better in CD performance when compared to DUV results. The AMTC has recently taken delivery of a full scale, production worthy, TEL photomask develop tool for use at future technology nodes.

Measurements of a scattering wave from a buried object were carried out at a site in Tokyo Bay. The buried object was set below the bottom with about 10-m water depth. A crane suspended a subbottom profiler to insonify the object. In these measurements, the medium frequency (less than 10 kHz) was used to penetrate near the critical angle. Also, when the object shape is a cylinder and so on, the scattering wave appears strongly in the specific direction, which is with the shape of the object and the physical relationship of the source and the object. The direction where this scattering wave appears is strongly different from the source position, and it is difficult to catch in the mono-static position. Especially, because the level of the scattering wave becomes low in the case of the scattering from the object under the seafloor, it is favorable if the scattering wave can be measured in the direction with this strong level. Therefore, to catch this strong scattering wave, an underwater vehicle was used. A hydrophone array was attached at the head of the underwater vehicle to accumulate over a series of pings. This report deals with the way and results of these measurements.