Maximizing common process latitude by integrated process development for 130-nm lithography

Abstract

Maximized inherent common process latitude of 130 nm line/space features through pitch is demonstrated in this work. It is shown that the principle method for doing so is by reducing the through pitch, or proximity, bias. The effects that formulation, illumination optics and mask error have on proximity bias are studied. Formulations exhibit a wide range of bias that does not necessarily depend upon activation energy or process temperatures. Optical settings for inner and outer sigma for both annular and quadrupole illumination, likewise, have a demonstrable effect on the proximity bias. Larger, tighter annuli or poles produce larger bias, while lower settings incur a loss of resolution. Either effect limits the common latitude so a balance is struck between them. Additionally, while the effect of outer sigma is obvious in the data, the inner sigma effect is not observed until data are corrected for mask error and the mask error factor. The proximity bias ranges between approximately 10 and 80 nm, depending upon the combination of conditions. Sub-resolution assist features (scattering bars) are specifically excluded from use in this experiment.

Calibration of ESCAP resist simulation parameters from consideration of printed CD pitch bias, CD measurement offset and wafer thermal history

“…In such cases, a simple Anhenius dependence is assumed such that P(T) = Ar exp( J (6) where P(T) a parameter which is a function of temperature A Anhenius constant Ea activation energy R = Universal gas constant T= Temperature in Kelvin It should be noted that for each temperature dependent value in PROLITH, the input values for the simulation are the activation energy and the natural logarithm ofthe Anhenius constant.…”

“…Figure 7 shows a plot ofthese values as a function oftime for the fully optimized fit. The values were calculated by substituting the wafer temperature into the Arrhenius equation (6). In the ideal bake scenario both diffusion and deprotection would start simultaneously, however in the situation shown in Figure 7, it is apparent that significant chemical amplification occurs before any diffusion.…”