ENERGY DEPOSITION BY SOFT X-RAYS - APPLICATION TO LITHOGRAPHY FOR VLSI

The energy deposited in x-ray irradiated low atomic number materials bounded by high atomic number elements can be much greater than the bulk dose. This effect has been studied for x-rays above 10 keV but the region below this energy has not been explored. The development of x-ray lithography for the mass production of integrated circuits with submicron linewidths, and the associated problems of energy deposition in sensitive regions of processed circuits, photoresists, and x-ray masks, has motivated the study reported here of dose enhancement effects in the low energy region. Computations were based upon a semiempirical model of energy deposition and charge transfer that had previously been successfully applied to soft x-ray emission (below 10 keV) and to energy deposition at high energies. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.