According to device shrinkage, pattern load, layout geometry and process induced critical dimension (CD) trend are the
most important factors deciding mask CD uniformity in a mask manufacturing process. The CD distribution is generally
divided by two categories - contribution of pattern load and process induced CD distribution. Etch bias uniformity on a
mask is one of the decisive contributors at a standpoint of pattern load. The signature of etch bias uniformity totally
depends on the pattern load in a mask. In a low pattern load, etch bias uniformity shows a radial signature which is
geometrically distributed regardless of pattern position. In a high pattern load, etch loading effect becomes dominant.
The pattern load, however, can have various definitions, which means that a criterion of low and high pattern load can be
obscure. Specific layouts which have same pattern load over mask but separated region of low and high load pattern in
one mask was designed to specify the effect of pattern load. The radial CD signature is mitigated as pattern load
increases locally. At the same time, etch loading trend grows and dominates total CD uniformity. The radial signature and
etch loading trend have inverse signs on central region which enables to compensate each signature. Therefore a specific
pattern load which can make etch bias uniformity minimized can exist. "Transition pattern load" is detected here. One
can use this specific pattern load as an indicator to specify design categories for mass production. In addition, geometry
of layout should be considered to achieve uniformity number required in 45nm node technology. In high pattern load
over transition pattern load, etch bias shows saddle shape uniformity. Since the saddle shape uniformity is uncorrectable
with conventional etch loading kernel, new correction model should be considered to meet the confined CD specification
in future device nodes.
The tight MTT control is required for the mask process of sub-50nm design node due to the complex OPC and
insufficient process margin. The MTT below 5nm is already required for the critical layers. Below 4nm is required for
sub-50nm node. In the viewpoint of this requirement, the MTT control is important for the mask fabrication.
According to the shrinking design node, the linearity is the main issue to satisfy MTT required. In the electron beam (ebeam)
lithography, the linearity results are strongly related to the resolution of the mask process. Isolated and dense
patterns have the different linearity behaviors due to the different contrast mainly caused by the backward scattering
contribution and develop process. Because of this reason, the conventional method of proximity effect correction (PEC)
optimization is unlikely to satisfy the MTT requirement. New PEC optimization is necessary for sub-50nm node.
In this report, new PEC optimization method is proposed. This method reduces the PEC error of conventional
optimization method known as a few nm. Because of the linearity, the error of conventional PEC optimization is
amplified according to the shrinking design. Therefore, the PEC error of conventional method is larger than the MTT
requirement for sub-50nm node. This new method is designed to overcome this problem. It takes into account for the
properties of each layer. Based on the analysis of composition of each layer, the different PEC optimization to fit the
each layer and design node is applied. It is able to be applied for the mask fabrication of sub-50nm memory device. The
improvement of MTT is achieved by the reduction of the PEC error with new PEC optimization.
In most of the video coding standards YCbCr color space is used as the input image format and most of the compression
techniques are reducing redundancies in each Y, Cb, Cr component plane. In this paper we introduce new inter color
prediction scheme that can further improve coding efficiency by exploiting the redundancy of chroma component within
a sequence. Simulation results show that the proposed algorithm can lead up to 20% of average bit-rate reduction or
equivalently 0.7dB quality improvement in chroma.