The crystal growth and haze formation on the reticle continue to be significant problems for the semiconductor industry. Recently, a pattern size has gradually reduced to enhance the integration of semiconductor device. As minimum linewidth has shrunk, the exposure wavelength has also progressively shrunk. The exposure wavelengths have been reduced progressively from g-line (436 nm), i-line (365 nm), KrF (248 nm), to ArF (193 nm). However, expose wavelength shrink caused some serious problems. One of the problems to be solved is growing defect in the reticle during the process. This growing defect on the reticle is called the haze. The haze is formed on both sides of the reticle, on the quartz side of the mask and on the chrome side of the mask. In this investigation, we varied the local haze defect size and the characteristics of the haze defect. And we get the critical dimension and the exposure latitude variation as the haze transmission changes and the haze phase shifts.
Chemically amplified resist materials are now available to reach critical dimensions of the pattern close to 32 nm values.
Pattern collapse is a very serious problem in fine patterning less than 32 nm critical dimension, because it decreases the
yield. The pattern collapse is the pattern response to unbalanced capillary forces acting on the pattern walls during the
spinning drying step after development process. Centrifugal force has not considered for pattern collapse modeling up to
now, so that pattern collapse due to spinning is studied. In this study we investigate the 32 nm node pattern collapse
mechanism with radial distance and rinse speed of dense patterns. In the process of creating the simulation tool, the
rotating model is used. As rinse speed and radial distance are increased, critical aspect ratio is decreased. As a result,
pattern collapse is increased.
Pattern collapse for line widths under 32 nm printed by extreme ultra-violet lithography (EUVL) is investigated by using commercial tools. Pattern collapse phenomenon occurs very often in actual process. Pattern collapse means that pattern is bending, peel-off, and break of the resist, thus it affects the production and yield of semiconductor. In this paper, we newly defined and investigated the critical aspect ratio. Pattern collapse happens if the critical aspect ratio is smaller than aspect ratio. Because EUV resist has smaller adhesive strength than currently available DUV and ArF resists, EUV resist easily collapse more easily than DUV resist does. This phenomenon is successfully modeled.
Extreme Ultraviolet Lithography (EUVL) is one of the patterning technologies proposed for the next generation lithography (NGL) which makes pattern less than 50 nm critical dimension (CD). And EUVL uses a very short exposure wavelength of 13.4 nm. So it has many characteristic in common with optical lithography, but EUVL are different from the conventional mask applied to the projection optical lithography. Specially, industry experts generally agree that the biggest challenges and risks for the next generation of lithography systems involve the mask. In EUVL, a mask is produced by applying multilayers of molybdenum and silicon to a flat substrate. The circuit pattern is produced by applying a final EUV-absorbing metal layer and then etching away the metal to form the image of the circuit. Also, the light shining with 6 degrees oblique to mask can not get target CD easily because the shadow effect is influenced on pattern. Therefore we must understand this kind of effect before doing real process. We tried to change the structure of the mask in order to decrease this effect and to have enough process latitude for the 32 nm node. EUV mask is affected by the thickness and kind of absorber and buffer material. First, we changed the absorber material such as Cr, TaN and Ge etc. without changing the buffer material. Second, we changed the thickness of the absorber materials. We tried to minimize the shadow effect by adjusting the side wall angle of the absorber layer parallel to the oblique incidence. Additionally we considered different shapes and depth of the etched multilayer binary mask and the refilled multilayer binary mask such as the inclined side wall of the etched multilayer. In this paper, we will describe the optimized EUV mask structure for 32 nm node by studying not only the aerial image, but also the resist profile. Solid-EUV simulator of Sigma-C is used to calculate the aerial image, resist pattern profile, and the process latitude with the optimized process parameters.