For the past years, ArF immersion has been employed as the major lithography tool in the foundry manufacturing to fabricate the patterns of minimum pitch and size. However, for semiconductor scaling beyond N7 the application of EUV lithography is considered to be crucially important to overcome the physical limitation of ArF immersion and to realize even smaller patterns. In the case of ArF photo processes, the best mask size for a specific pitch could be selected with the consideration of optical performances such as NILS, MEEF, etc. In contrast, for the EUV processes the optical and resist stochastic effect should also be taken into account as an important factor in deciding the best mask size. In this paper, we are going to discuss the dose and mask size optimization process for an DRAM contact hole layer with EUV lithography utilizing stochastic simulations; this contains also the stochastic response of the resist. In order to calibrate a predictive stochastic resist model, which is required for this application, measurements of the stochastic resist response are necessary. In addition, the systematic and stochastic errors of CD-SEM measurements have to be estimated. We will compare experimentally obtained NILS and MEEF to simulated results, which are in very good agreement. Also, we show a comparison of experimental and computational analysis of LCDU (Local CD Uniformity).
As critical dimensions for advanced two dimensional (2D) DUV patterning continue to shrink, the exact process window becomes increasingly difficult to determine. The defect size criteria shrink with the patterning critical dimensions and are well below the resolution of current optical inspection tools. As a result, it is more challenging for traditional bright field inspection tools to accurately discover the hotspots that define the process window. In this study, we use a novel computational inspection method to identify the depth-of-focus limiting features of a 10 nm node mask with 2D metal structures (single exposure) and compare the results to those obtained with a traditional process windows qualification (PWQ) method based on utilizing a focus modulated wafer and bright field inspection (BFI) to detect hotspot defects. The method is extended to litho-etch litho-etch (LELE) on a different test vehicle to show that overlay related bridging hotspots also can be identified.
A diffractive optical modulator has been fabricated based on a micromachining process. Novel
properties of its fast response time and dynamics were fully understood and demonstrated for the
strong potentials in embedded mobile laser display. Bridged thin film piezo-actuators with so called
open mirror diffraction structure has been designed. Optical level package also was achieved to
successfully prove its display application qualities. Display circuits and driving logic were developed
to finally confirm the single-panel laser display at a 240Hz VGA (640×480). With its efficiency of
more than 75% and 13cc volume optical engine with the MEMS-based VGA resolution SOM
showed 7 lm brightness at a 1.5W electrical power consumption. Detailed design principle,
fabrication, packaging and performances of the invented SOM are described.
In this paper, two different methods of double exposure are proposed to improve the resolution in low k1 lithography. One is using an additional mask to complement the lack of image contrast. The other is to fix the mask and only use combinations of illumination systems to increase image contrast. By applying image assisting double exposure to asymmetry dense contact under k1=0.33, the process window can be doubled in comparison to the single exposure method. By an appropriate design of two masks, we could also minimize the image distortion from overlay shift by mixture of masks. Effective first order efficiency is defined as a new term in double exposure with complementary illumination. The larger the value is, the better the image contrast becomes. Through an experiment and simulation in k1=0.30, in double exposure with two illuminations and the same mask, that wider process window was obtained than in single exposure with optimized illumination system, and also 0.10um of DOF (Depth of Focus) was obtained under k1=0.28.