| 摘要註: |
(1) 當半導體微影製程光源從使用193 nm (DUV, Deep ultraviolet)波長縮短至13.5 nm (EUV, Extreme ultraviolet)波長時，光阻釋氣即被視為汙染 EUV 光學元件的重要元兇之一。微影製程曝光機台由 DUV 穿透視鏡頭組演進至 EUV 多層膜反射式鏡頭組，當反射鏡反射 EUV 光源的同時也會反射雷射電漿光源所產生的 DUV out of band (OOB)的雜光，此雜光會造成光阻成像的對比度(contrast)降低，亦會增加未經評估的光阻釋氣問題。另外，前趨微影製程將再縮短光源波至6.7 nm (BEUV, Beyond extreme ultraviolet)，在此微影製程發展的同時光阻材料與光阻厚度亦會隨之改變。故本實驗研究光阻材料、光阻厚度、光源能量對光阻所造成之中性釋氣物種現象，並量測經 EUV 與 BEUV 光源照射下光阻中性釋氣速率。本實驗使用四極桿質譜儀(QMS, quadrupole mass spectrometer)進行不同光阻材料於不同光源照射下，中性釋氣物質定性與定量研究，光阻薄膜材料為 PMMA 及 DuPont’s 公司所提供 EUV 模型光阻，光源來自國家同步輻射中心 BL04B1-Seya (DUV、VUV)及 BL08A1-LSGM (EUV、BEUV)光束線。測得的釋氣質譜圖將以 NIST 網站提供分子於70 eV 電子游離質譜資料庫，使用質譜消去法鑑定與分析釋氣物種與分佈量。本研究為第一個使用 BEUV 光源對 PMMA 及 EUV 模型光阻進行定性與定量量測之團隊；並成功地將不同材料、不同厚度之光阻於 EUV 光源照射下測得定量結果與本團隊先前實驗結果及 SEMATECH 團隊研究結果進行標竿評比。定性研究發現光阻釋氣物種分佈與光阻厚度無明顯相關。光阻釋氣物種與分子結構相關，傳統型光阻 PMMA 的釋氣斷片主要來自 MMA 單體及側鏈的甲基甲酯，斷鍵主要由 Chain scission、Norrish type reaction 及 Ester elimination 三種機制組成；在 DUV/VUV 及 EUV/BEUV 光源照射下各主要釋氣物種分別來自 Chain scission 與 Norrish type I 的反應路徑。含有 tertbutyl acrylate 的 EUV 模型光阻釋氣斷片主要來自去保護基及光酸陽離子，斷鍵主要由 Norrish type I reaction及 Ester elimination 機制組成；在 DUV/VUV 及 EUV/BEUV 光源照射下各主要釋氣物種皆來自於 Ester elimination，與光照能量無相關。光阻釋氣速率在膜厚約80 nm 以下時與膜厚呈正相關，亦即光阻的釋氣逃脫厚度約在80 nm 附近，由 PMMA 的 EUV 與 BEUV 之絕對釋氣速率推估，光子與二次電子所造成的釋氣現象約為一釋氣事件需吸收 ~14.5 eV 及 8.5 eV能量。(2)在本論文第一部分光阻薄膜經光照射所產生之釋氣現象中發現光阻釋氣物種及釋氣量與光吸收及光阻結構相關，EUV 模型光阻所產生的主要斷片來自於支鏈的Norrish type I 及 Ester elimination 而非苯環本身的斷裂。本實驗室黃彥翔學長曾研究12種有機小分子電子游離與光游離的離子產物絕對分支比，得知未含苯環的有機酯類斷鍵絕大部分是經由 RC(O)O-R’ 或 R-C(O)OR’ 的途徑。本研究將量測六種含苯有機分子電子游離與光游離的離子產物絕對分支比，並和先前研究12種有機小分子電子游離與光游離的結果比較，探討苯環經光或電子解離游離所帶來的影響。由結果可知(1)含有苯環與不含苯環的有機化合物中抵抗電子游離的能力排序皆為:醇類 > 酮類 > 酯類；(2)含苯環有機分子保有母離子的比列皆大於不含苯環的有機分子，此表示苯環具較大的光與電子游離抵抗能力，有穩定分子的作用。本實驗使用四極桿質譜儀量測電子游離與光游離的離子產物絕對分支比，電子游離源為 QMS 本身的燈絲游離源，光游離源則使用國家同步輻射中心 BL04B1-Seya 光束線。電子游離測得的質譜圖將與 NIST 及 MSSJ 網站所提供分子於70 eV 電子游離質譜資料庫做標竿比較，結果證實本實驗與 NIST 及 MSSJ 資料庫資料僅存在儀器間的不準確度，而無系統性誤差，此亦支持本論文第一部分以 NIST 質譜圖分析中性釋氣物種的可信賴度。電子游離選用的能量範圍為10~150 eV；光子游離選用的能量範圍為8~40 eV。所得結果之分子解離游離的分支比順序與反應的相對反應生成熱順序呈正相關。 (1) When the semiconductor microlithography light source evolved from 193 nm (DUV, Deep ultraviolet) into 13.5 nm (EUV, Extreme ultraviolet) era, resist outgassing is considered one of the major reasons leading to optics contamination, which is a new issue to EUV microlithography. From DUV to EUV lithography, optical systems have been changed from a transmission type to a reflection type, unavoidably, the EUV reflective mirrors will also reflect DUV out of band (OOB) stray light, which can cause an image contrast loss and put in additionally unexpected resist outgassing. A further reduction of the lithographic wavelength to 6.7 nm (BEUV, Beyond extreme ultraviolet) is emerging, and BEUV resist photochemistry is an un-explored subject. We thus studied outgassing upon DUV, VUV, EUV and BEUV irradiation.We characterized the distribution of outgassed species as a function of film thickness, radiation energy, and polymeric structures. We further measured resist outgassing rates with a quadrupole mass spectrometer (QMS). The resist samples included polymethyl methacrylate (PMMA) and two DuPont’s EUV model resists. This work was conducted at the BL04B1-Seya and BL08A1-LSGM beamline of National Synchrotron Radiation Research Center (NSRRC) in Taiwan.To our knowledge, this is the first measurement of PMMA and EUV model resists outgassing rate at BEUV. A benchmark comparison revealed that absolute outgassing rates of PMMA and EUV model resists determined by this work were consistent with values provided by our previous work and SEMATECH groups. Thus, we have effectively demonstrated that the Taiwanese facility is capable of evaluating absolute resist outgassing rates, making it one of limited facilities worldwide for evaluating EUV resist outgassing. We found that the distribution of outgassed species was not thickness dependent, whereas outgassing rates were film-thickness dependent for samples of less than 80 nm in thickness. Outgassing species branching ratios were wavelength dependent. As energy increased the extent of fragmented outgassing increased. Major outgassed species from conventional photoresist PMMA were identified mainly as MMA monomer and side chain outgassing of methyl formate, its bond cleavage can be characterized from chain scission, Norrish type reaction and Ester elimination. Upon DUV/VUV and EUV/BEUV irradiation, PMMA favor to chain scission and Norrish type I reaction, respectively. Outgassing from EUV model resist came mostly from deprotection groups and photoacid generator cations, its bond cleavage mainly came from determined from Norrish type I reaction and ester elimination, and it is wavelength independent upon DUV/VUV and EUV/BEUV irradiation that EUV model resist both favor to ester elimination reaction. A quantitative assessment on the absolute outgassing rates from PMMA suggested an outgassing escape length in the order of 80 nm and that PMMA takes ~14.5 and ~8.5 eV to generate unit outgassing upon EUV and BEUV irradiation, respectively.(2)In the first part of this thesis, I demonstrated that major outgassed species of EUV model resists came mainly from Norrish type I and ester elimination, and that the distribution of outgassed species and outgassing rate can be correlated with photoabsorption and the compositions of photoresists. |