Double-patterning techniques

Designed to overcome the problem of printing at small pitches, double-patterning techniques typically comprise those techniques in which two cycles each of 

Conley, and I. Liu, Challenges of 29 nm half pitch patterning with 193 nm dry lithography 

Hendrckx, and J.V. Olmen, Manufacturability issues with double patterning for 50 nm half pitch single damascene applications, using RELACS shrink and corresponding OPC, Proc. SPIE 6520, 652001 (2007) W. Y. Jung, S. M. Kim, C. D. Kim, G. H. Sim, S. M. Jeon, S. W. Park, 

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Figure 17.15 Process sequence for LELE double-patterning technique.

Figure 17.16 SEM cross section of 25-nm half-pitch lines patterned with LELE double-patterning technique. The line profiles were obtained after the final pattern transfer to the underlying substrate. The second-layer patterns after the second etch step are considerably longer than the first-layer patterns because they are capped with the second HM material. (Courtesy of S. Holmes.)...

Figure 17.17 Process sequence for LFLE double-patterning technique.

Figure 17.19 Process sequence for self-aligned double-patterning technique by means of sidewall spacer formation.

Figure 17.20 SEM images of shallow trench isolation structures patterned with self-aligned double-patterning technique through various stages of the process flow, and ending in 22-nm half-pitch structures. The HM used is Applied Materials Corporation s advanced patterning film (APF). ...

Double exposure is commonly used to pattern features in the same layer that are different or have incompatible densities or pitches. A good example might he the simation where two exposures are made such that one exposure is used to define features oriented in one direction, while the other exposure is used to define the other set of features oriented in another direction that is perpendicular to the first direction. In this way, two-dimensional patterns can be decomposed into two one-dimensional patterns, which are considerably easier to print. In other words, the double-exposure technique enables the patterning of minimum pitch feamres... 

The spacer double-patterning approach has some issues, the main one of which concerns placement accuracy of the features, which requires excellent dose and etch uniformity control. Equally problematic is the fact that the spacers may not stay in place at the proper location after the material to which they are attached (the HM pattern) is removed. Forming acceptable uniform spacer profiles that will yield uniform CDs is not a trivial exercise. In addition, the etch pattern transfer steps, often involving delicate removal of materials adjacent to the spacers, place unusually tight etch process tolerance on this technique, in order to have a successful outcome. 

Thermal waves have relatively shallow penetration into a material surface flaws tend to cause heat to diffuse at a different rate from that of the surrounding material [68]. In thermographic testing, two techniques exist, the single-sided technique and the through-transmission or double-sided test. In the former, which is more sensitive to flaw depth indication, only the test area scanned is heated (Eig. 4), while the double-sided technique uses the transmission characteristics of a heat pulse passing through a thin section of composite material [64], Temperature patterns at the surface of a composite arc produced... 

SPIO-enhanced MRI is particularly helpful for the evaluation of the tumor burden of the liver in case of the diffuse growth pattern of HCC. In doubtful cases an MR examination with both SPIO and gadolinium contrast agents (so-called double-contrast technique) can be useful [7, 28, 56], although this practice falls in the category of off-label use. 

Selective decoupling spin-spin interactions by the double resonance technique. The sample is simultaneously irradiated with two radio-frequency fields one frequency gives the resonance pattern of interest, and the other frequency is the resonance frequency of the coupled nuclei. When the second proton is irradiated with sufficient intensity, the spin-spin coupling collapses giving simple spectra. 

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