A visualisation and proximity correction tool for submicron E-beam lithography

This paper describes an interactive visualisation CAD package, XPROX, which has been developed to simulate and visualise the exposures of submicron pattern features in E-beam lithography. XPROX provides visualisation and iterative proximity correction for different pattern shapes and exposure conditions. For patterns comprising a large number of shapes, where there is a need to identify the proximity effect in critical areas quickly and automatically, a technique is described using XPROX whereby only the critical areas are proximity corrected, thus saving significantly on computing resources and data preparation time.     

电子束光刻中邻近效应校正的几种方法

本文简要介绍了限制电子束光刻分辨率的主要因素之一-邻近效应的产生机制,列举了校正邻近效应的GHOST法、图形区密集度分布法和掩模图形形状改变法,介绍了每种方法的原理、步骤和效果,比较了它们各自的优缺点.     

Implementation of electron beam grey scale lithography and proximity effect correction for silicon nanowire device fabrication

An electron beam lithography exposure strategy combining efficient proximity effect correction (PEC) with multi-pass grey scale is compared with a more conventional strategy based on a single-pass exposure without PEC. Exposure results for different types of nanowire structures are presented. Line edge and line width roughness (LER and LWR) values for both approaches are determined. The novel exposure strategy presented in this work reduced LER by ∼25% and LWR by ∼40%.     

图形改正方法在邻近效应修正中的应用

本文利用双高斯形式的邻近函数来表达电子束在抗蚀剂中能量的分布,并以邻近函数为基础计算一些简单图形在曝光时所需的尺寸改变量.通过与实验的比较来说明该方法的可靠性,并对所得结果进行讨论和分析.     

Trades-off between lithography line edge roughness and error-correcting codes requirements for NAND Flash memories

The only way to keep pace with Moore’s Law is to use probabilistic computing for memory design. Probabilistic computing is ‘unavoidable’, especially when scaled memory dimensions go down to the levels where variability takes over. In order to print features below 20 nm, novel lithographies such as Extreme Ultra Violet (EUV) are required. However, transistor structures and memory arrays are strongly affected by pattern roughness caused by the randomness of such lithography, leading to variability induced data errors in the memory read-out. This paper demonstrates a probabilistic–holistic look at how to handle bit errors of NAND Flash memory and trades-off between lithography processes and error-correcting codes to ensure the data integrity.     

Improving the sensitivity and line edge roughness in inorganic positive electron beam resist

Need for inorganic electron beam resist with higher sensitivity and resolution is indisputable. We have developed such a resist that also shows lower line edge roughness. It is pre-baked at 300 °C. By using 4 kV EB we have delineated 40 nm lines pattern and honeycomb structure Photonic crystal pattern.     

Improved safety and efficacy in adaptive control of arterial bloodpressure through the use of a supervisor

A dual approach to adaptive control of arterial blood pressure using sodium nitroprusside is presented. In the clinical environment, a controller must be aggressive to achieve specific step response characteristics (less than 10 min setting time, less than 10 mm Hg overshoot), yet conservative enough to prevent overreactions to large disturbances, which are common in both the operating room and the intensive care unit. These mutually exclusive requirements make it difficult to design a closed-loop controller for this environment. To prevent possible overreactions while maintaining proper step response, an aggressive adaptive controller has been designed to achieve the desired step response, and a supervisor has been designed around the adaptive controller to limit potential overreactions in the presence of disturbances. Simulations and dog experiments demonstrate the potential for increased safety and efficacy using this dual approach to the control of a complex physiological system     

Improved method for suppression of ambiguity in measurements of permittivity in low and high loss materials with short-circuited line technique

A procedure to suppress the ambiguity in the complex dielectric permittivity which arises when using the short-circuited line method is described. Results of the procedure for several organic liquids with low and high losses are presented.<>     

Capacity analysis in downlink WCDMA systems using soft handover techniques with SIR-based power control and site selection diversity transmission

This paper analyzes the downlink performance of a wideband code-division multiple-access system with site selection diversity transmission power control during soft handover (SHO) mode. Signal-to-interference ratio power control techniques are modeled and used in the simulations of this analysis. The study is focused on finding the optimum SHO margin in terms of maximum system capacity under energy-per-bit to noise spectral density ratio (E/sub b//N/sub 0/) quality requirements. The results of this analysis show an increase in user capacity of about 15%-20% for optimum SHO margins of 5-5.5 dB. Nevertheless, the resources required (number of scrambling codes) by the base station increase faster than the number of active users in terms of SHO margin up to values of approximately 9.5 dB.     

Retransmission control and fairness issue in mobile slotted ALOHA networks with fading and near‐far effect

The effects of different retransmission control policies on the performance of a mobile data system employing the slotted ALOHA protocol are investigated, with the emphasis on the unfairness between close-in and distant users due to the near-far effect. An analytical multi-group model is developed to evaluate both the user and the network performance of the mobile slotted ALOHA network under two classes of retransmission control policies, namely the Uniform Policy and the Nonuniform Policy. The Uniform Policy requires that all users adopt the same retransmission probability, whereas the Nonuniform Policy allows more distant users to have larger retransmission probability in order to compensate for the unfairness caused by the near-far effect. The performance of a slotted ALOHA network with a linear topology in a Rician fading channel under the two policies is compared by the multi-group model and simulation. The Nonuniform Policy is found to be more effective in alleviating the unfairness of user throughput over a wider range of the data traffic load than the Uniform Policy, which is effective only when the data traffic load is very light. Thus, a mobile data network can enjoy the network performance improvement derived from the near-far effect while the unfairness between close-in and distant users can be greatly mitigated without resorting to power control. This revised version was published online in June 2006 with corrections to the Cover Date.