Generation of Tin-Doped Droplets for EUV Generation
Date Issued
2012
Date
2012
Author(s)
Li, Jing-Sheng
Abstract
The stability of extreme ultraviolet (EUV) source relies on the droplets target system to provide stable droplets, expecting to achieve the goal of high conversion efficiency and low debris. To achieve this goal, this thesis employs the well developed technology of inkjet printing to generate stable droplets target as EUV source.
In the present study, we focus on the optical coherence tomography (OCT) application instead of applying the generated EUV light source in conventional semiconductor manufacturing. Therefore, the required EUV energy does not have to reach the level of 100W for high volume semiconductor manufacture. The droplet size and frequency are determined by the energy and the repetition rate of the laser pulses, hoping that we could make the laser pulses hit one by one on the center of the droplets target synchronously to fully ionize the droplets, and release high quality of the EUV light source.
In this thesis, we hope to apply the continuous jet breakup method to generate high repetition rate droplets. The experiment is conducted as follows: First, we use deionized water and find out the most suitable parameter for inkjet printing at 20-kHz repetition rate under a pressure of 18 psig. Then we apply the same parameter to conduct the experiment by using 5% KOH solution and diluted 9.55 wt.% SnO2 solution. Finally, we elevate the concentration of SnO2 solution to 17.5 wt.% and successfully generate the stable droplets. The only factor need to be adjusted is the back pressure and the pressure is P=26.2 psig.
This thesis use the squeeze mode piezoelectric inkjet printhead which is produced by MicroFab (Model No.MJ-AT-01) and construct a droplets target generator especially designed for EUV generation. Most studies used the same MicroFab printhead to generate droplets by applying the Drop-on-demand method at low repetition rate (below 2,000 Hz), but seldom mentioned about how to use the continuous jet breakup method to generate stable and high repetition rate droplets. This thesis shows a pioneer work to build up the tin-doped droplets target generator by using the squeeze mode piezoelectric inkjet printhead and applying the continuous jet breakup method to eject droplets at high repetition rate above 20 kHz, and find out a set of parameter for the stable droplets.
Subjects
Extreme Ultraviolet
EUV
Lithography
Tin-Doped droplet
Inkjet printing
SnO2
Continuous Jet Breakup
Squeeze Mode printhead
capillary tube
instability breakup
MicroFab MJ-AT-01
synchronization
Rayleigh instability
colloid
nanoparticle suspension
stannic chloride
soft x-ray
13.5nm EUV
OCT
Optical Coherence Tomography
Drop-on-demand
DoD
PZT
piezoelectric printhead
Type
thesis
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