Large area electron scattering effects on SCALPEL mask critical dimension control

• Published in: Microelectronic engineering Vol. 57; pp. 505 - 510
• Main Authors: Nordquist, K., Resnick, D.J., Ivin, V., Mangat, P., Lu, B., Masnyj, Z., Ainley, E., Dauksher, W.J., Mancini, D., Silakov, M., Minyushkin, D., Vorotnikova, N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2001
• Subjects: Critical dimension control; Large area electron scattering effects; SCALPEL mask; SCALPEL mask; Critical dimension control; Large area electron scattering effects
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/S0167-9317(01)00541-X

One promising technology for next generation lithography is the electron projection technique called SCALPEL. Relatively thin membrane and scattering materials are required for high contrast imaging during SCALPEL wafer exposures. The thin SCALPEL membranes allow a majority of the electrons to pass when exposing the masks at high accelerating voltages (>50 keV). Critical dimension (CD) control and uniformity is complicated by the contribution from large area electron scattering characteristics (‘fogging’ effect) of the material below the membrane mask. Depending on the material type, morphology and distance of the backing material from the membrane, the electron scattering contribution can be significant and cover a wide radius from the exposure pixel. The energy contribution associated with various materials, morphology and positions underneath a 200-mm SCALPEL membrane mask were investigated. The energy contribution was determined via Monte Carlo simulations and added to a resist exposure/process simulation model to determine the impact on CD results. The simulated and actual CD results are compared for various materials at two different distances from the membrane for verification of the model accuracy. Simulation and experimentation also revealed the electron trapping effect with various aspect ratio via holes did not significantly reduce the electron backscatter contribution to the resist features.