EUV resist processing with flash-lamp

Abstract

The reduction of line width roughness (LWR) remains a difficult issue for very fine patterns obtained with extreme ultraviolet (EUV) lithography. Thus, the investigation of LWR-reduction from the viewpoint of resist processing has become necessary. Alternative bake processes, such as the flash-lamp (FL) has been proven feasible as for application in EUV resists. This work focuses on initial investigations for its use in post-development bake (post bake or PB). A polyhydroxystyrene-acryl hybrid EUV model resist was utilized and comparisons with 'no bake' and conventional hot-plate PB conditions were made. As a result, relatively improved LWR was obtained with FL PB with minimal effect on lithographic performance. Moreover, in the course of these experiments, two types of resist reflow mechanisms assumed to be the primary basis for the LWR improvement achieved, are discussed.

Resist Materials and Processes for Extreme Ultraviolet Lithography

“…16) In the search for possible solutions, a trend on the optimization of presently available conventional resist processes has been observed. [8][9][10]17,[95][96][97][98][99] Understanding the sufficiency of present processes and possibly the need for the development of new or alternative processes will be especially important in moving forward to extremely stringent targets required for next-generation semiconductors. 16) Here, we review the development and present status of various alternative resist processes that are proposed for improving LWR/LER.…”

“…To break the RLS trade-off relationship, a number of groups 8,9,17,98) over the past few years have started and continue investigations on and search for alternatives in the presently available resist processes. Figure 8 shows the various EUV resist process steps discussed in this paper.…”

“…One example of the thermal smoothing process is the FL-based postbake (FL PB) process. 9) Here, the resist-coated wafer is irradiated with a Xe-based light source, which allows baking at very high temperatures for a very short time (<3 ms). Preliminary investigations have shown the potential of the FL PB process in LWR reduction.…”

“…In particular, the effect and possible solutions to the trade-off relationship between EUV resist targets, namely, resolution, LWR/LER, and sensitivity, which have been constant topics in EUVL, [8][9][10]14,17) are described and reviewed. Recent works on resist materials focusing on conventional and nonconventional chemical platforms 1,4,5,[11][12][13]18,19) are also discussed.…”

“…Recent advances in these materials and process technologies are largely credited to the cooperation and focused efforts of various sectors of the resist community (e.g., industry consortia, universities, and material/ tool manufacturers). 1,[4][5][6][7][8][9][10] Specifically, industry consortia such as Selete, SEMATECH, IMEC, and recently, EIDEC have and continue to promote very conducive research environments for device manufacturers, universities, resist resin/material suppliers, and tool manufacturers. Such collaborations have led to the investigation and realization of new and exciting resist platforms 5,[11][12][13] and processes.…”