As improving device integration for the next generation, high performance and cost down are also required
accordingly in semiconductor business. Recently, significant efforts have been given on putting EUV
technology into fabrication in order to improve device integration. At the same time, 450mm wafer
manufacturing environment has been considered seriously in many ways in order to boost up the productivity.
Accordingly, 9-inch mask has been discussed in mask fabrication business recently to support 450mm wafer
manufacturing environment successfully. Although introducing 9-inch mask can be crucial for mask industry,
multi-beam technology is also expected as another influential turning point to overcome currently the most
critical issue in mask industry, electron beam writing time. No matter whether 9-inch mask or multi-beam
technology will be employed or not, mask quality and productivity will be the key factors to survive from the
device competition. In this paper, the level of facility automation in mask industry is diagnosed and analyzed
and the automation guideline is suggested for the next generation.
Strong resolution enhancement techniques (RETs) are highly demanded to overcome the resolution limit of sub-60nm lithography. ArF immersion lithography may be the best candidate for sub-60nm device patterning. However, the polarization effect becomes more prominent to degrade the image quality in high NA immersion lithography as the feature size shrinks. Therefore, it is important to understand the polarization effect in the mask. The induced polarization effect shows the different aspects between the binary and the attenuated phase shift mask (PSM). In this paper, we considered the effects of polarization state as a function of mask properties. We evaluated the performances of the binary mask and the attenuated PSM by using simulation, AIMS<sup>TM</sup> (Aerial Image Measurement System) tool, and real wafer printing. We find out that there are no differences between the binary mask and the attenuated PSM in view of image contrast and mask error enhancement factor (MEEF).
CD(Critical Dimension) Non-Uniformity on a mask is normally separable into global and local CD errors by means of their error sources. In general a global CD error trend on a mask shows the properties of each process. On the other hand, local CD errors on a mask are pretty much random and caused from mainly measurement errors, LER(Line Edge Roughness), and litho-shot errors. However, because of its difficulty to pin point the sources of errors and correct them, the local CD errors are required more attention. A Global CD error trend on a mask can be classified into several groups. One originating from vacuum delay, lithography error, bake and etch process will cause a side error trend on a mask. Others are fogging, radial trends of develop, and etch loading. In order to classify all those global CD errors and local CD errors, the proper monitoring mask must be required. The works on this paper mainly focalize on minimizing global CD error trends on a mask by separating and analyzing error components with proper monitoring system of each process. We therefore, provide a monitoring mask designed for efficiently representing global and local CD errors in more detailed fashion which can analyze CD errors of each process and make feed-back to each process in order to improve each process of mask manufacturing.
In this article, we analyzed in-field uniformity (IFU) on wafer considering exposure margin [linewidth variation (nm) per % exposure dose variation (%)] and the MEEF (mask error enhancement factor). As gate linewidth becomes smaller, the controllability of in-field uniformity (IFU) plays a key role in wafer manufacturing yield. IFU depends on various lithography parameters including mask CD (critical dimension) uniformity, MEEF, exposure margin, focus margin, transmittance, flare and illumination uniformity. In real world, the combination of wafer exposure machine and mask characteristics should be carefully considered to achieve better IFU on wafer. This presentation discusses the various experimental works including CD uniformity on mask, IFU on wafer, MEEF, exposure margin and wafer exposure machine. CD uniformity data on mask and IFU data on wafer is obtained from optical measurement tool to reduce measurement error disregarding local CD variation. Even though one handles a unit pattern, various MEEF exists in a unit pattern in case of complex pattern. In addition, the MEEF varying with the area across one mask degrades IFU on a wafer. IFU on a wafer is predictable using mask CD uniformity and exposure margin mean. Variation of exposure margin is the measure of stability of photo process. In manufacturing devices, mask and Litho. Tool should be well harmonized to achieve better IFU and a higher manufacturing yield. The photo process including resist process should be well controlled to get stability, as well as mask CD uniformity.
Haze is a kind of surface contamination on photomask and lithography optics that made by photochemical reaction. There are many problems in photomask manufacturing, inspection and lithography process because of slowly growing feature of haze. In the photolithography process, the wafer damage has been occurred due to the time dependent growth of haze. In this study, we identified the origin and formation mechanism of haze using accelerated contamination experiments, also developed control method for haze, in which the removal efficiency was confirmed by mass production of photomask. From these results we expect that the photocontamination control technology should be developed and been an important part of NGL technology.