Can fast rule-based assist feature generation in random-logic contact layout provide sufficient process window?

Omran, Ahmed; Lippincott, George; Schacht, Jochen; Lei, Junjiang; Li, Hong; Friedrich, Loran; Shen, Regina; Chou, Ryan

doi:10.1117/12.915787

Cited by 3 publications

(2 citation statements)

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“…These additional shapes are narrow lines or small rectangles placed adjacent to primary shapes in order to create denser and more uniform environment that facilitates relatively isolated primary features show more dense-like behavior [4]. The placement, size and shape of SRAFs have to be carefully optimized to maximize their positive effect on the manufacturability and at the same time prevent them from transferring to photoresist.…”

Section: Motivationmentioning

confidence: 99%

A stochastic approach to SRAF printing prediction

Lutich

2014

SPIE Proceedings

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In this paper we discuss a statistic approach to SRAF printing detection. This method considers and is generically based on the opportunistic essence of the resist image formation due to various stochastic uncertainties in the state-of-the-art advanced node lithographic process. The method is based on the direct measurement of the probability of SRAF printing at considered-to-be-nominal conditions and extrapolation of the results based on the process conditions/assumptions to the probability ranges where direct probability measurements are practically impossible. The method described here provides a controllable and quantitative framework for setting up SRAF printing detection and facilitates the significant reduction of the efforts and costs needed to setup SRAF printing checks. The argumentation and the way of looking at the verification setup in the environments with considerable variability can be directly reused to design and calibrate other checks in OPC verification flows.

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Section: Motivationmentioning

confidence: 99%

A stochastic approach to SRAF printing prediction

Lutich

2014

SPIE Proceedings

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“…The sub-resolution assist feature (SRAF) added adjacent to the main feature based on the design rule or model is one of the typical techniques used to enhance the process window of the lithography process [ 19 ]. The rule-based approach designs the SRAF’s layout by referring a table to decide the size, number, and relevant distances of the assist features according to the CD and pitch of the main feature [ 20 , 21 ], while the model-based approach is based on the computed result of simulation or inverse lithography technology [ 22 , 23 ]. In this study, the OPE-caused CD shrink is observed at the edges of various phase change material line arrays, irrespective of the line density of the array.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Phase Change Material Array by Sub-Resolution Assist Feature for Storage Class Memory Application

et al. 2023

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High density phase change memory array requires both minimized critical dimension (CD) and maximized process window for the phase change material layer. High in-wafer uniformity of the nanoscale patterning of chalcogenides material is challenging given the optical proximity effect (OPE) in the lithography process and the micro-loading effect in the etching process. In this study, we demonstrate an approach to fabricate high density phase change material arrays with half-pitch down to around 70 nm by the co-optimization of lithography and plasma etching process. The focused-energy matrix was performed to improve the pattern process window of phase change material on a 12-inch wafer. A variety of patternings from an isolated line to a dense pitch line were investigated using immersion lithography system. The collapse of the edge line is observed due to the OPE induced shrinkage in linewidth, which is deteriorative as the patterning density increases. The sub-resolution assist feature (SRAF) was placed to increase the width of the lines at both edges of each patterning by taking advantage of the optical interference between the main features and the assistant features. The survival of the line at the edges is confirmed with around a 70 nm half-pitch feature in various arrays. A uniform etching profile across the pitch line pattern of phase change material was demonstrated in which the micro-loading effect and the plasma etching damage were significantly suppressed by co-optimizing the etching parameters. The results pave the way to achieve high density device arrays with improved uniformity and reliability for mass storage applications.

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