Contact edge roughness and CD uniformity in EUV: effect of photo acid generator and sensitizer

2013

A contact hole pattern as well as a line-and-space pattern is a basic element for the fabrication of semiconductor devices. The critical dimension uniformity and edge roughness of contact hole patterns are critical issues for extreme ultraviolet (EUV) lithography. In this study, the quality of the latent images of contact hole patterns was investigated in terms of the chemical gradient using a simulation on the basis of the reaction mechanisms of chemically amplified EUV resists. The latent image formation of contact hole patterns was compared with that of line-and-space patterns. The latent image quality of contact hole patterns was significantly lower than that of line-and-space patterns. To obtain the same latent image quality as line-and-space patterns, the exposure dose should be increased 1.4±0.1 times. Similarly to the line-and-space patterns, the increase of acid generator concentration and effective reaction radius is effective for the enhancement of latent image quality. For the enhancement of latent image quality of contact hole patterns, the enhancement of the effective reaction radius is more effective in a low exposure dose region than a high exposure dose region.

Chemical Gradient of Contact Hole Latent Image Created in Chemically Amplified Extreme Ultraviolet Resists

2013

Stochastic Effect on Contact Hole Imaging of Chemically Amplified Extreme Ultraviolet Resists

2013

With the near realization of extreme ultraviolet (EUV) lithography, the critical dimension uniformity and edge roughness of contact holes have attracted much attention. In this study, the stochastic effect on contact hole patterns was investigated using a Monte Carlo method on the basis of the reaction mechanisms of chemically amplified EUV resists. The standard deviation of the number of protected units did not depend on exposure dose or acid generator concentration under the process conditions optimized in terms of the chemical gradient. However, the standard deviation of the number of protected units depended on the effective reaction radius for deprotection.

Acid diffusion length in contact hole imaging of chemically amplified extreme ultraviolet resists

2013

Contact holes and line-and-space patterns are the most basic elements in the fabrication of semiconductor devices. In this study, the chemical processes in contact hole imaging were investigated to clarify the optimum acid diffusion length in terms of the quality of latent images. The chemical processes were simulated using a Monte Carlo method based on the reaction mechanisms of chemically amplified extreme ultraviolet (EUV) resists. The theoretical dependence of the optimum acid diffusion length on the exposure dose and half-pitch (diameter) was clarified. At an exposure dose of 20 mJ cm−2, the optimum acid diffusion length (three-dimensional) was 10.7 nm for 28 nm contact holes (56 nm pitch). By decreasing the diameter to 16 nm (32 nm pitch), the optimum acid diffusion length (three-dimensional) was decreased to 8.9 nm, which was smaller than that of line-and-space patterns by 12%. The chemical reactions for the dissolution of resist polymers should be sufficiently induced within these acid diffusion lengths for contact hole imaging.