Proximity effect (electron beam lithography)

About: Proximity effect (electron beam lithography) is a research topic. Over the lifetime, 940 publications have been published within this topic receiving 8508 citations.

Three-dimensional proximity effect correction for large-scale uniform patterns

Abstract: One of the major limiting factors in electron beam (e-beam) lithography is the geometric distortion of written features due to electron scattering, which is known as the proximity effect. A conventional approach to the proximity effect correction (PEC) is, through 2D simulation, to determine the dose distribution and/or shape modification for each feature in a circuit pattern such that the written pattern is as close to the target pattern as possible. Earlier, it was shown that the 3D PEC, which considers the variation of exposure along the resist-depth dimension, would be necessary for the feature size well below 100 nm. Also, a feature-by-feature correction procedure is too time-consuming to be practical, especially for the 3D PEC of large-scale patterns. In this paper, a new method for the 3D PEC is proposed, which adopts 3D resist profile (instead of 2D exposure distribution) in optimization, but avoids the intensive computation by employing a critical-location-based correction procedure. The proposed...

An image processing approach to fast, efficient proximity correction for electron beam lithography

Abstract: A limitation on the quality of electron beam lithography is the proximity effect. This produces exposure of the resist at locations remote from the point of incidence of the electron beam. One of the techniques used to mitigate this problem is to precompensate the applied beam dose. Traditional approaches to this problem have required extensive calculations which occasionally fail to produce satisfactory results. However, the proximity correction problem is quite similar to the edge enhancement problem which arises in pattern recognition. Furthermore, the issue of data base compaction for the precompensated lithography is quite similar to bandwidth compression in image transmission. In this paper, we examine the application of image processing methods to the proximity correction problem. We find that, while the match between these disciplines is not perfect, the idea appears quite promising.

Applicability of extreme ultraviolet lithography to fabrication of half pitch 35nm interconnects

Abstract: Extreme ultraviolet lithography (EUVL) is moving into the phase of the evaluation of integration for device fabrication. This paper describes its applicability to the fabrication of back-end-of-line (BEOL) test chips with a feature size of hp 35 nm, which corresponds to the 19-nm logic node. The chips were used to evaluate two-level dual damascene interconnects made with low-k film and Cu. The key factors needed for successful fabrication are a durable multi-stack resist process, accurate critical dimension (CD) control, and usable overlay accuracy for the lithography process. A multi-stack resist process employing 70-nm-thick resist and 25-nm-thick SOG was used on the Metal-1 (M1) and Metal- 2 (M2) layers. The resist thickness for the Via-1 (V1) layer was 80 nm. To obtain an accurate CD, we employed rulebased corrections involving mask CD bias to compensate for flare variation, mask shadowing effects, and optical proximity effects. With these corrections, the CD variation for various 35-nm trench and via patterns was about ± 1 nm. The total overlay accuracy (|mean| ± 3σ) for V1 to M1 and M2 to V1 was below 12 nm. Electrical tests indicate that the uses of Ru barrier metal and scalable porous silica are keys to obtaining operational devices. The evaluation of a BEOL test chip revealed that EUVL is applicable to the fabrication of hp-35-nm interconnects and that device development can be accelerated.

Charged particle beam drawing apparatus and method

Abstract: A charged particle beam drawing apparatus has a drawing chamber including a movable stage which supports a mask, the mask being formed by applying a resist to an upper surface of a mask substrate, an optical column for applying a charged particle beam to draw patterns in the resist, a charged particle beam dose correction portion for correcting a dose of the charged particle beam applied from the optical column to the resist on the basis of proximity effect and fogging effect, and a conversion coefficient changing portion for changing a conversion coefficient on the basis of pattern density in the resist and a position in the resist, wherein the conversion coefficient is a ratio of an accumulation energy of the charged particle beam accumulated in the resist, to an accumulation dose of the charged particle beam accumulated in the resist.