|
Early insertion of ArF nm lithography will occur at the 130 nm node in 2001. Process development for the 100 nm node will also occur this year. Both aggressive gate length reductions and minimum pitch design rules below 250 nm present immediate challenges for the new ArF technology. Gate line widths with approach one half of the wavelength of the exposure system. Contact holes and dark field mask trench structures for 100 nm node will require use of high NA ArF scanners as well as advanced illumination conditions. Development of processes utilizing OPC and PSM as well as advanced illumination conditions are critical to achieving adequate resolution, process latitude, and CD control. With the introduction of very low k1 processes the pattern collapse problem that was anticipated for NGL lithography is upon us today. Another result of sub-wavelength patterning and low contrast images is that the CD variation in the photomask gives rise to a larger than expected printed CD changes: the so-called MEEF (Mask Error Enhancement Factor). The MEEF can be defined as the slope of the litho process linearity curve. This paper will address pattern collapse and CD control issues for bright and dark field images using a full field ArF scanner. We will demonstrate that the resist choice, dark field and bright field printing, feature size and pitch, process conditions, as well as illumination conditions influence the process non- linearity and MEEF. We will compare this with resolution capability and MEEF of modern KrF resist and attempt to quantify the maturity of ArF resist technology. The CD range of 90 - 140 nm is studied using binary masks, as well as alternating and attenuated PSM masks with ArF exposure. We will examine the possibility of optical proximity corrections for dark field structures with low and high MEEF.
|
