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.

Evaluation of the practical use of GHOST technique for various e-beam resists

Abstract: In this paper we present results of the application of the GHOST technique to the practical use with 10 keV system. Three commercial e-beam resists which include ZEP7000, PBS, and EBR9 HS31 are selected for comparisons. The background dose equalization by the GHOST technique was found to be effective in reducing the proximity effect. It is generally assumed that exposure contrast degradation due to secondary exposure with largely defocused beam for the GHOST technique, especially at boundary between pattern pixel and nonpattern pixel, leads to poor CD uniformity. Thus, we examined CD uniformity variations as a function of with and without the GHOST technique for three e-beam resists .And we also reported the comparison of proximity effect correction quality for three resists by looking at CD linearity in order to investigate relationship between proximity effect and resist contrast.

Electron beam exposure method

Abstract: PURPOSE:To suppress the influence of electrons of an electron beam reflected from a substrate and form a dense, fine pattern where no proximity effect is recognized by preparing a resist having a sensitivity which is inferior to that of an upper layer resist at a lower layer, thereby making the resist have a two-layer resist structure; namely lower and upper layer resists CONSTITUTION:Lower and upper layer resists 2 and 3 are coated on a silicon substrate 1 It is preferable for the lower layer resist to have sensitivity that is inferior to that of the upper layer resist Once the resist is irradiated by an electron beam, the upper layer resist is sufficiently exposed to the electron beam but the lower resist is not exposed to its beam Then the electron beam is reflected to the silicon substrate and even the lower resist is also exposed to its beam Being different from the case of a single layer resist 3 the arrangement of another resist 2 having inferior sensitivity makes the influence of reflected electrons small The resultant cross section obtained after its development exhibits a large undercut in the case of the single layer resist as shown by dotted lines 5 but a small undercut in the case of the two-layer resist as shown by solid lines 6

Investigation of proximity effects for a rim phase-shifting mask printed with annular illumination

Abstract: Resolution enhancement techniques have been explored extensively in the last few years in attempts to reliably extend optical lithography to smaller features. Off-axis illumination has shown remarkable success improving the depth of focus for dense lines and spaces. However, the depth of focus for isolated lines is degraded. This paper shows experimental results of 0.22 micrometers lines at varying pitch printed with a rim phase-shifting mask on a GCA DUV stepper with 0.53 NA and annular illumination of 0.6 - 0.7 (sigma) . Although the results demonstrate a depth of focus of greater than 1.0 micrometers , there are severe proximity effects which cause a 60 nm difference between the dimension of dense versus isolated lines. We hypothesize that this proximity effect is caused by three physical phenomena, the aerial image itself, reflections from the silicon substrate, and acid diffusion in the APEX-E (IBM) resist. Simulation results are presented which show that of the 60 nm linewidth difference, 10 nm is due to the image, 10 nm is caused by substrate reflections, and 40 nm is the result of acid diffusion in the resist.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Impact of proximity model inaccuracy on patterning in electron beam lithography

Abstract: Electron beam lithography is a promising technology for next generation lithography. Compared to optical lithography, it has better pattern fidelity and larger process window. However, the proximity effect caused by the electron forward scattering and backscattering in the resist and the underlying substrate materials has a severe influence on the pattern fidelity when the required critical dimensions (CD) are comparable to the electron beam blur size. Therefore, an accurate electron scattering model and a proper proximity correction play a vital role in electron beam lithography. In this paper, we describe the model accuracy of electron scattering in terms of multiple Gaussian kernels with an in-house proximity error correction to reduce proximity error with much better accuracy and more self-consistency than the double Gaussian kernel on the 100-keV electron energies. The impact of various Gaussian kernels used in the proximity correction on the lineation of typical patterns is also addressed.