An investigation on the process control for the solid application of EUV MOR

Abstract

Metal oxide resists (MORs) have been becoming one of the most promising candidates that facilitates the extension of EUV single exposure by improving both lithographic resolution and etch selectivity. However, to succeed high volume manufacturing, the MORs process should be robust and persistent regardless of lithographic process fluctuation that might occur. In this work, the systematic examinations on the MORs process have been explored in order to understand the MORs patterning mechanism. We found that the ADI CD (After Development Inspection Critical Dimension) could be varied with trivial fluctuation of EUV radiation, humidity, and incomplete condensation reaction. In particular, the humidity around a coated resist was the important element that affected the condensation reaction and determined the insolubility of MORs against developer solution, which consequently defines the ADI CD. Thus, the methods that enable not only the moisture control but the sufficient condensation reaction were carefully examined. Moreover, it is investigated whether MORs can enhance further the etch selectivity while reducing the intrinsic resist defect. Several strategies have been implemented, which allow the CD variation to be reduced and the process window to be enlarged compared to the early stage MORs processes.

Thermal deformation variations with field positions on the wafer and resist types (CAR and MOR)

“…Basically, MOR is an inorganic photoresist consisting of chemically bonded tin oxygen cluster structures. 9 But it is very hard to finding its material property so that we instead used the tin. For the MOR, a 30 nm-thick was used.…”

Extreme Ultraviolet Lithographic Performance and Reaction Mechanism of Polymeric Resist─Utilizing Radical- and Acid-Amplified Cross-Linking

“…Several resist platforms with high EUV absorption cross section, containing metals such as Sn, Hf, Zr, and Sb, have also been reported. − Apart from high absorption, the ligands around the metal core in MOR offer numerous reaction sites which can increase sensitivity by the efficient use of secondary electrons. They showed resolution down to 10 nm using a 0.5 numerical aperture (NA) Berkeley microfield exposure tool (BMAT) and interference lithography. , However, due to the presence of moisture in ambient, the critical dimensions (CD) printed with MOR vary from wafer to wafer . It has been shown that the postcoating delay can cause fluctuations in CD up to 10% .…”

“…They showed resolution down to 10 nm using a 0.5 numerical aperture (NA) Berkeley microfield exposure tool (BMAT) and interference lithography. , However, due to the presence of moisture in ambient, the critical dimensions (CD) printed with MOR vary from wafer to wafer . It has been shown that the postcoating delay can cause fluctuations in CD up to 10% . Apart from the above, there are other resists such as scission-based resistone example of which is PMMA.…”

Organic dry development rinse (O-DDR) process for spin-on MOR to prevent pattern collapse

“…EUV lithography is an advanced semiconductor manufacturing technique that utilizes extreme ultraviolet radiation to create intricate patterns. Metal oxide resist is crucial in such sophisticated lithography processes for achieving high resolution and precise pattern formation [1][2][3]. The high thermal stability required in EUV lithography necessitates resist materials that can withstand elevated temperatures.…”