Y. Iba et al., ORIGIN OF STRESS-DISTRIBUTION IN SPUTTERED X-RAY ABSORBER FILM, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 15(6), 1997, pp. 2483-2488
To eliminate distortion in x-ray masks, not only lower average stress
but also uniformity of the stress distribution in the x-ray absorber f
ilm are very important. We investigated the cause of stress distributi
on in sputtered x-ray absorber films both theoretically and experiment
ally. Our investigation clarified that stress distribution is determin
ed by the distribution of the average velocity of sputtered and workin
g gas atoms and/or the arrival frequency of incident working gas atoms
when arriving at the wafer in sputtering systems. These determinants
are strongly influenced by the geometry of the sputtering apparatus, i
.e., the shape of the erosion area of the target and the substrate-to-
target distance. We obtained a good uniformity of stress by optimizing
the sputtering equipment configuration taking the erosion area of the
target into consideration. Two ways to accomplish this are by adjusti
ng the gap between the target and the substrate and by achieving unifo
rmity of the erosion area. (C) 1997 American Vacuum Society.