Improving resist performance by PROMOTE processing

摘要

Abstract: In PROMOTE processing of novolac-diazonaphtoquinone (DNQ) resists, a deep UV flood exposure is given under water-free conditions during the post exposure bake. When exposure is done under water-free conditions DNQ forms an ester with the novolac, which is insoluble in TMAH. Due to the high absorption of the resist for the DUV flood exposure wavelength, ester is mainly formed in the top of the formerly unexposed regions. With DRM measurements it is shown that PROMOTE can enhance both development contrast and, due to the ester gradient in the depth of the resist, profile slopes. Therefore, dyed resist processing benefits more from PROMOTE than transparent resist, especially when degradation of the top of the resist profiles is the limiting factor, i.e., near the resolution limit of the stepper/resist combination, PROMOTE is advantageous. When the development process is left unchanged, the improvement with PROMOTE is attained at the expense of a higher imaging dose. An alternative for a higher imaging dose is a more aggressive development process, which can be achieved by a longer development time or a higher normality developer. The best results with PROMOTE are obtained when a more aggressive development process is used. !9