Corrections to proximity effects in electron beam lithography. I. Theory

1979 ◽  
Vol 50 (6) ◽  
pp. 4371-4377 ◽  
Mihir Parikh
2000 ◽  
Vol 636 ◽  
Kenneth E. Gonsalves ◽  
Hengpeng Wu ◽  
Yongqi Hu ◽  
Lhadi Merhari

AbstractThe SIA roadmap predicts mass production of sub-100 nm resolution circuits by 2006. This not only imposes major constraints on next generation lithographic tools but also requires that new resists capable of accommodating such a high resolution be synthesized and developed concurrently. Except for ion beam lithography, DUV, X-ray, and in particular electron beam lithography suffer significantly from proximity effects, leading to severe degradation of resolution in classical resists. We report a new class of resists based on organic/inorganic nanocomposites having a structure that reduces the proximity effects. Synthetic routes are described for a ZEP520®nano-SiO2 resist where 47nm wide lines have been written with a 40 nm diameter, 20 keV electron beam at no sensitivity cost. Other resist systems based on polyhedral oligosilsesquioxane copolymerized with MMA, TBMA, MMA and a proprietary PAG are also presented. These nanocomposite resists suitable for DUV and electron beam lithography show enhancement in both contrast and RIE resistance in oxygen. Tentative mechanisms responsible for proximity effect reduction are also discussed.

T. H. Newman ◽  
R. F. W. Pease ◽  
K. J. Polasko ◽  
Y. W. Yau

Two prominent problems of electron beam lithography are slow throughput and proximity effects. The former arises from the serial nature of the exposure process; the current available in a beam of given resolution is limited by electron optical considerations and the resist sensitivity is limited by material considerations such that a dose of 1 μC/cm2 at 20 kV is required for the most sensitive resist and ten times that dose if high resolution is required.Proximity effects are caused by electrons scattered through lateral distances greater than the resolution of the pattern; a 20 keV electron in silicon has a range of about 3 μm whereas feature sizes are often less than 1 μm. Lowering the energy of the exposing electrons to, say, 2 keV would lower the electron range to less than 0.1 μm in silicon and thus effectively eliminate proximity effects as far as semiconductor circuit fabrication is concerned.

TJ. Stark ◽  
Z. J. Radzimski ◽  
P.A. Peterson ◽  
D.P. Griffis ◽  
P. E. Russell

Recent advances in electron optical systems which allow reduction of electron beam voltage while maintaining sufficiently small spot size and high current density have opened new possibilities for electron beam lithography. The main advantage of low beam energy lithography is a reduction of backscattered electrons and, consequently, the reduction of problems associated with proximity effects. The other advantages of this technique are reduction in the dose required to modify a resist and minimization of substrate damage caused by energetic electrons. Proper electron energy must be chosen at which the beam deposits its energy mainly within the resist film with minimal penetration into the substrate. Monte Carlo simulation programs have been used widely to predict the scattering interactions and thus the area of proximity effects. Rutherford cross section for angle scattering and Bethe energy loss have been commonly used in Monte Carlo modeling. However, low energy lithography (<5keV) requires a more accurate approach based on Mott cross sections for scattering and a more precise formula for energy loss replacing the Bethe law which is invalid below 1 keV energy.

1993 ◽  
Vol 20 (4) ◽  
pp. 255-275 ◽  
A. Ouabbou ◽  
J.P. Martinez ◽  
F. Lalanne ◽  
P. Gérard ◽  
J.L. Balladore

Sign in / Sign up

Export Citation Format

Share Document