Helen Wang

Double exposure double etch for dense SRAM: a designer's dream

As SRAM arrays become lithographically more aggressive than random logic, they are more and more determining the lithography processes used. High yielding, low leakage, dense SRAM cells demand fairly aggressive lithographic process conditions. This leads to a borderline process window for logic devices. The tradeoff obtained between process window optimization for random logic gates and dense SRAM is not always straightforward, and sometimes necessitates design rule and layout modifications. By delinking patterning of the logic devices from SRAM, one can optimize the patterning processes for these devices independently. This can be achieved by a special double patterning technique that employs a combination of double exposure and double etch (DE2). In this paper we show how a DE2 patterning process can be employed to pattern dense SRAM cells in the 45nm node on fully integrated wafers, with more than adequate overlap of gate line-end onto active area. We have demonstrated that this process has adequate process window for sustainable manufacturing. For comparison purpose we also demonstrate a single exposure single etch solution to treat such dense SRAM cells. In 45nm node, the dense SRAM cell can also be printed with adequate tolerances and process window with single expose (SE) with optimized OPC. This is confirmed by electrical results on wafer. We conclude that DE2 offers an attractive alternative solution to pattern dense SRAM in 45nm and show such a scheme can be extended to 32nm and beyond. Employing DE2 lets designers migrate to very small tip-to-tip distance in SRAM. The selection of DE2 or SE depends on layout, device performance requirements, integration schemes and cost of ownership.

Medical sieve: a cognitive assistant for radiologists and cardiologists

Radiologists and cardiologists today have to view large amounts of imaging data relatively quickly leading to eye fatigue. Further, they have only limited access to clinical information relying mostly on their visual interpretation of imaging studies for their diagnostic decisions. In this paper, we present Medical Sieve, an automated cognitive assistant for radiologists and cardiologists designed to help in their clinical decision-making. The sieve is a clinical informatics system that collects clinical, textual and imaging data of patients from electronic health records systems. It then analyzes multimodal content to detect anomalies if any, and summarizes the patient record collecting all relevant information pertinent to a chief complaint. The results of anomaly detection are then fed into a reasoning engine which uses evidence from both patient-independent clinical knowledge and large-scale patient-driven similar patient statistics to arrive at potential differential diagnosis to help in clinical decision making. In compactly summarizing all relevant information to the clinician per chief complaint, the system still retains links to the raw data for detailed review providing holistic summaries of patient conditions. Results of clinical studies in the domains of cardiology and breast radiology have already shown the promise of the system in differential diagnosis and imaging studies summarization.

Graphene plasmons: properties and applications

I will discuss the optical properties and possible applications of graphene in photonics and plasmonics. I will review the basics of the single particle and collective excitations of graphene, discuss the mechanisms of photocurrent generation in graphene and the design and characteristics of graphene-based photodetectors. I will show that the coupling of light to localized graphene plasmons provides an excellent way of enhancing the strength of graphene-light interaction. Plasmon excitations in graphene micro- and nano-structures and their use in graphene devices in the infrared and terahertz ranges of the EM spectrum will be discussed. The interactions of graphene plasmons with intrinsic graphene and substrate phonons and their implications will also be analyzed.