新穎感光樹脂之製備與性質研究

Abstract

在感光樹脂研究中，已知藉由氫鍵作用讓分子先行排列，可使感光基互相靠近而加快光聚合反應速度。在我們先前的研究中，也觀察到多面體矽氧烷化合物(polyhedral oligomeric silsesquioxane，簡稱POSS)的siloxane基和OH基間存在氫鍵。因此，我們延伸之前的研究，希望開發高感度的感光樹脂。本論文分為四部份研究：(1)將POSS結構導入感光性共聚高分子，再配製成負型光阻；(2)直接將單壓克力官能基POSS化合物混摻入負型光阻中；(3)直接將五氟苯乙烯混摻入負型光阻中；(4)將單壓克力官能基POSS化合物混摻入紫外光硬化樹脂組成物中。然後探討感光樹脂的特性。

(1)在第二章研究中，製備一系列感光性共聚高分子，含有POSS結構和甲基丙烯酸酯(methacrylate)感光官能基，由甲基丙烯酸(methacrylic acid)、甲基丙烯酸甲酯(methyl methacrylate)、異丁基丙基甲基丙烯醯基多面體矽氧烷(isobutyl propylmethacryl polyhedral oligosilsesquioxanes，簡稱MI-POSS)經過自由基共聚合反應，再和甲基丙烯酸環氧丙酯(glycidyl methacrylate)反應而得。感光性共聚高分子化學結構以1H-NMR和FT-IR光譜確認。由微差掃描卡計(DSC)和熱重分析儀(TGA)分析結果顯示，感光性共聚高分子的玻璃轉化溫度和熱安定性會隨著POSS含量增加而增加。紫外光/可見光光譜儀(UV/VIS)測試結果可看到感光性共聚高分子因加入POSS而稍微降低透光性，在365nm波長透光率由99%微降至92.5%。進一步將感光性共聚高分子、壓克力多官能基單體、光起始劑配製為光阻評估光阻性質。由評估結果發現，含POSS光阻的感度(sensitivity，Dn0.5)、對比(contrast， )、光硬化速率等光阻性能，都比未含POSS光阻提昇許多。photo-DSC分析顯示，導入POSS使反應起始時間(induction time)由0.020 min降至0.015 min。

(2)在第三章研究中，配製一系列負型光阻，固定感光性共聚高分子(不含POSS)、壓克力多官能基單體、光起始劑的組成量，變化MI-POSS混摻量，並探討其光阻特性。我們發現含POSS光阻的感度(sensitivity)、對比(contrast)、光硬化速率等光阻性能，都比未含POSS光阻提昇許多。結果與第二章類似，但是提升效率稍差。

(3)在第四章研究中，延伸第三章研究，將MI-POSS改為五氟苯乙烯，並探討其光阻特性。我們發現含五氟苯乙烯光阻的感度(sensitivity)、對比(contrast)、光硬化速率等光阻性能，都比未含五氟苯乙烯光阻提昇許多。結果與第三章類似。

(4)在第五章研究中，配製二系列含POSS的紫外光硬化樹脂組成物，由Bisphenol A propoxylate glycerolate diacrylate(簡稱PGDA)或Bisphenol A propoxylate diacrylate(簡稱PDA)單體加上MI-POSS單體和光起始劑Irgacure 907所組成。利用FTIR光譜和photo-DSC，探討分子結構和分子間氫鍵作用對光聚合反應速率和放熱量的影響。結果顯示PGDA系列光聚合速度和放熱量均小於PDA系列。PGDA單體的壓克力官能基上含有OH官能基，因為分子結構的關係，雖然形成分子間氫鍵，壓克力官能基容易受氫鍵限制無法自由運動與緊密靠近，反而不利光聚合反應。混摻MI-POSS，即使只是小量，卻可以聚集壓克力官能基，對光聚合速率有提昇效果。PDA單體不含OH基，加入MI-POSS混掺，只是逐漸稀釋壓克力官能基密度，對光聚合速率沒有提昇效果。

由以上觀察結果，可以合理的解釋為hydroxyl-siloxane或hydroxyl-carbon fluorine bond間氫鍵交互作用，使含OH基的壓克力雙鍵聚集在POSS或pentafluorostyrene結構周圍，有助於光硬化反應，因而加強光硬化反應速度、感度等感光樹脂性能。我們也利用平行曝光機評估光阻的微影性質(lithographic property)，發現本論文光阻適合高感度紫外光微影技術之應用。

It has been reported that the photopolymerization rates of photoresists capable of forming hydrogen bonding are significantly enhanced due to the pre-organization via hydrogen bonding to bring reactive bonds closer each other. In our previous study, we have observed the existence of hydrogen bonding interaction between the siloxane of the polyhedral oligomeric silsesquioxane (POSS) moiety and the hydroxyl groups. Accordingly, we would like to extend our previous works to develop new photosensitive resins with enhanced sensitivity, higher contrast, and better resolution. In this dissertation, POSS-containing negative-type photoresists were prepared by copolymerization and blending methods, then characterized. Fluorine-containing negative-type photoresists by blending method and POSS-containing photocurable resins were also studied. (1) In chapter 2, a series of methacrylate copolymers containing POSS were synthesized from the free radical copolymerization of methacrylic acid, methyl methacrylate, and isobutyl propylmethacryl polyhedral oligosilsesquioxanes (MI-POSS) and then were modified with glycidyl methacrylate to serve as negative-type photoresists. The UV/VIS spectroscopy reveals that the incorporation of POSS moiety into the copolymer results in slight decrease in transparency from 99% to 92.5 % (at wavelength = 365 nm). The photosensitivity in terms of resist sensitivity, contrast and photopolymerization rate are significantly increased with increasing of the POSS content. In addition, the induction time is reduced from 0.020 to 0.015 min after incorporating POSS unit based on the photo-DSC analyses. (2) In chapter 3, a series of negative type photoresists were prepared by blending different MI-POSS content and studied the photosensitive properties. The photosensitivity and photo-polymerization rate results which go up with an increase in MI-POSS content are similar to previous chapter’s study with slightly less efficiency but better processibility. (3) In chapter 4, a series of negative type photoresists were prepared by blending different pentafluorostyrene content and studied the photosensitive properties. The photosensitivity and photo- polymerization rate results which go up with an increase in pentafluorostyrene content are also similar to previous chapter’s study. (4) In chapter 5, two series of POSS-containing photocurable resin compositions were prepared and studied by FTIR spectroscopy and differential photocalorimetry. With fixed photoinitiator concentration, increasing proportions of MI-POSS were added to either bisphenol A propoxylate glycerolate diacrylate (PGDA) or bisphenol A propoxylate diacrylate (PDA). The photopolymerization rate and enthalpy of PGDA compositions are significantly smaller than PDA compositions. As POSS concentration increased, the photopolymerization reactivities of PGDA compositions increased, while the photopolymerization reactivities of PDA compositions continued decreasing with increasing POSS concentration. The strong influence of molecular structure and hydrogen-bonding interaction on photopolymerization rate and conversion was discussed. These observed results can be rationalized hydrogen bonding interaction between hydroxyl-siloxane or hydroxyl-carbon fluorine bond tends to attract the double bonds surrounding POSS or pentafluorostyrene units, thereby enhancing the photo-polymerization rate and sensitivity. We further evaluate the lithographic property of photoresists under a collimated exposure. High sensitivity photoresists made in this dissertation have potential utility for UV-lithography.