Fabrication of Tin Loaded Resorcinol Formaldehyde Aerogel Spheres for Extreme Ultraviolet Source Emission
- PDF / 805,289 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 56 Downloads / 180 Views
0961-O14-02
Fabrication of Tin Loaded Resorcinol Formaldehyde Aerogel Spheres for Extreme Ultraviolet Source Emission Reny R. Paguio, Abbas Nikroo, Chris A. Frederick, Jared F. Hund, and Mary Thi Inertial Fusion Technology, General Atomics, P.O. Box 85608, San Diego, CA, 92186-5608
ABSTRACT Low density Sn doped resorcinol formaldehyde aerogels were fabricated for extreme ultraviolet (EUV) source emission lithography experiments (EUVL). EUVL is a candidate to succeed conventional optical lithography. EUVL requires a reliable emission (13.5 nm) source. One type of source is a laser-produced plasma. Several laser-plasma source materials have been considered such as lithium, xenon and tin. Tin is considered ideal because it has a high conversion efficiency. However, solid tin targets create a large quantity of debris which can damage the optics of the laser system. As a solution to this problem, we minimized the amount of tin by dispersing it in a low density resorcinol formaldehyde (R/F) matrix. These targets were fabricated into small spheres using the microencapsulation method. Initial experimental results show that these targets yield a similar intensity in the EUV regime when compred to a full density Sn target. INTRODUCTION Low-density tin loaded foams or aerogel spheres are needed for extreme ultraviolet (EUV) source emission experiments for extreme ultraviolet lithography (EUVL) [1,2]. EUVL is a candidate to succeed conventional lithography, but a reliable EUV emission source is needed [3,4]. One possible source is laser produced plasma [1–4]. In this source, a laser hits a target which produces an emission in the EUV range of 13.5 nm. Several EUVL targets have been considered such as lithium, xenon and tin [1–4]. Tin is considered ideal because it has a high conversion efficiency (>3%) of incident laser energy into EUV light [1-2]. However, solid
tin targets create debris problems which can damage the laser optics. As a solution to this problem we minimized the amount of tin by dispersing it in a low density matrix [1,2]. We fabricated these targets by loading a known amount of SnO2 into a resorcinol formaldehyde (R/F) aerogel precursor solution and forming this solution into aerogel spheres using microencapsulation [5-7]. The diameter of these tin loaded spheres have been cotrolled in a range from 100–600 µm. Fabrication of these Sn loaded aerogel spheres is a direct extension of work done to fabricate both hollow and solid aerogel spheres for inertial confinement fusion experiments [5–10]. EXPERIMENTAL R/F aerogel was first developed by Pekala, et al. [11]. Synthesis begins with a precursor solution that is formed into an aerogel by a polycondensation reaction using a two-step (base/acid catalysis) gelation shown in Figure 1 [5,7–9,11]. By controlling solvent and precursor quantities the density can be controlled. The hydrogel is supercritically dried to prevent shrinkage and cracking of the resulting aerogel. We have extended this work by loading the aerogel with Sn by dispersing and suspending a small a
Data Loading...
