產生極紫外光源所需之摻錫液滴靶材之研究

Generation of Tin-Doped Droplets for EUV Generation

李璟昇(Jing-Sheng Li)

指導教授 ： 黃升龍

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00452

摘要

極紫外光源仰賴穩定的液滴系統使光源得以穩定產生，期能達到高轉換效率與低殘留餘渣(Debris)之目標，為達此要求，本研究使用現今已發展成熟的噴墨技術(Inkjet Printing)，提供能產生穩定且乾淨的極紫外光源所需的液滴靶材。
由於產生的光源並非應用於半導體量產，而係希望用於生醫影像光學同調斷層掃描，故所需的EUV能量毋須達到半導體量產所需的100瓦等級，液滴大小與頻率皆視雷射的能量與重複頻率所決定，期能達到雷射脈衝與液滴以一對一同步的方式打在靶材正中心，以達完全游離，放出高品質的極紫外光源之目標。 本實驗希望以連續水柱斷裂的方式產生高重覆頻率的液滴，首先，先以純水為溶液，在20 kHz之重覆頻率、18 psig壓力下找出最佳噴墨的雙極脈衝波形，接著，再以同樣的參數噴摻錫溶液之溶劑5% KOH與稀釋後9.55 wt.%的摻錫溶液，能順利噴出後，最後，濃度再往高調至17.5 wt.%的摻錫溶液，唯一改變的參數為氣壓，調高至P=26.2 psig，即可順利噴出穩定液滴，液滴尺寸約噴口大小的兩倍左右。
本實驗以MicroFab公司生產的型號MJ-AT-01的擠壓式壓電噴頭，架設一套專為產生極紫外光源所需的液滴靶材產生系統，文獻研究多以此MicroFab噴頭以低重複頻率(2千赫茲以下)Drop-on-demand的方式來產生液滴，而很少提到如何以連續水柱斷裂的方式來產生穩定且高重覆頻率的液滴，本實驗是第一個以擠壓式壓電噴頭，用連續水柱斷裂方式噴出高重複頻率達2萬赫茲以上的摻錫溶液液滴靶材，並找出一組穩定噴墨的最佳參數，為產生極紫外光源所需的液滴靶材系統提供一個重要的參考。

關鍵字

極紫外光 ； 微影術 ； 摻錫液滴 ； 噴墨技術 ； 二氧化錫 ； 連續水柱斷裂 ； 擠壓式壓電噴頭 ； 毛細管

並列摘要

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.

並列關鍵字

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

參考文獻

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