一般正型感光性聚苯噁唑 (Polybenzoxazole；PBO) 聚合物是藉由Diazonaphthoquinone (DNQ) 改質之聚羥醯胺 (Polyhydroxyamide；PHA) 所組成，但普遍具有較高的熱膨脹係數，在半導體元件製作上，會造成光阻劑與基板的熱膨脹係數差異過大，而造成不匹配(mismatch) 現象，再經過高溫熱處理後，容易使表面形成翹曲或是脫裂。因此，本研究將透過導入直鏈且剛硬的單體，來降低熱膨脹係數，提升機械強度，並且以 DNQ 改質，配製出一具有低熱膨脹係數且正型感光性光阻劑系統。
本研究合成方法採低溫聚合反應，藉由2,2-bis(3-amino-4-hydroxy phenol)hexafiouoropropane (BisAPAF)、isophthaloyl chloride (IC) 和Terephthaloyl chloride (TC)三種單體共聚形成聚苯噁唑(Polybenzoxazole；PBO) 之前驅物聚羥醯胺 (PHA)，將其於350 ℃ 高溫環化後可形成聚苯噁唑 (PBO) 作為 IC 晶片保護膜。
本實驗藉由改變 IC 及 TC單體的合成比例來降低高分子的熱膨脹係數 (CTE)，再與 BisAPAF 單體反應，所得到的PHA經高溫環化 (curing) 反應後可得到熱膨脹係數小於30 ppm/℃ 的聚苯噁唑(Polybenzoxazole；PBO)。由熱機械分析 (TMA) 可得知 CTE 隨著 TC單體添加量增加而下降，但透光度在紫外-可見光光譜分析可知PHA 的穿透度隨 TC 單體添加量增加而降低。
利用聚羥醯胺與 1,2-naphthoquinonediazide-5-sulfonyl chloride (DNQ-5)感光物質進行反應，藉由部份 OH 基被保護之作用下來抑制在鹼性水溶液中的溶解速率。此正型感光材料在 2.38 wt% 四甲基氫氧化銨 (TMAH) 的顯影液中，其未曝光區的溶解速率與已曝光區相比有明顯地降低，故此感光材料具顯著的低未曝光部份的膜損失 (dark film loss) 而可形成一良好的光阻劑。
再利用部份 OH 基被保護的聚羥醯胺，添加感光材料 PIC-3 做為溶解抑制劑所製成的感光材料，可以製成高解析度、低未曝光膜損失的正型鹼性水溶液顯影的耐高溫感光高分子材料。在 2.38 wt% 四甲基氫氧化銨 (TMAH) 的顯影液中測得感光度為 332 mJ/cm2，對比值達 5.3，未曝光膜損失為 2 %。顯影後的聚羥醯胺圖案在 350 ℃ 下環化處理三小時後即可轉化為聚苯噁唑 (PBO)。以光學顯微鏡 (OM) 和掃瞄式電子顯微鏡 (SEM) 觀察顯影後的圖案，解析度可達 5 μm。證實本研究所製備的正型光阻材料可應用於微影製程，並且擁有低熱膨脹係數的性質。

Five different ratios of Polybenzoxazole (PBO) precursors poly (hydroxy amide) (PHA) was synthesized by 2,2-Bis(1,3-amino-4-hydroxyphenyl)hexafluoropropane (BisAPAF), Terephthaloyl chloride (TC) and Isophthaloyl chloride (IC). When subjected to thermal cyclization, PHA can convert to PBO film. Both PHAs and PBOs were measured by FT-IR, TGA, TMA, and other method. The inherent viscosities of PHAs were in the range of 0.4~0.54 dL/g. After curing, these polybenzoxazoles (PBOs) showed CTE and Tg in the range of 26~32 ppm/°C and 321~338 °C, respectively. The polybenzoxazoles (PBOs) also showed good thermal stability, with 5-% weight loss temperature being recorded above 500 °C in air atmosphere. We also use 1,2-naphthoquinonediazide-5-sulfonyl chloride (DNQ-5), which caused some phenol hydroxyl groups of PHA to be protected, and 2,3,4-tris(1-oxo-2-diazonaphthoquinone-5-sulfonyloxy)-benzophenone (PIC-3) as a dissolution inhibitor. The PSPBO consisting of DNQ capped PHA, PIC-3, exhibited a sensitivity of 332 mJ/cm2, a contrast of 5.3 and a dark film loss of 2-% developed in 2.38 wt% Tetramethylammonium hydroxide. A clear positive image of the PBO pattern was obtained after curing at 350 °C with 5 μm resolution. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to observe the resulting patterns.

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