Process Instruction

The synthesis of the copolymers was optimized and allows a simple and environmentally friendly production of the resists. Similarly, almost no differences could be observed for a bake of films between 150 – 180 °C, while the contrast decreases at a temperature of 95 °C. Depending on the respective samples, the Cauchy coefficients were determined in a range of 1.541 – 1.544. Sensitivity, gradation and resolution can be influenced to a great extent if different developers are utilized. Plasma etch stability is similar to the commercial photoresist and two times better to the PMMA. In summary, our investigations demonstrated that the CSAR shows a high sensitivity, high resolution and good plasma etch stability and can be used to generate excellent lift-off structures.The optimization of non-CAR samples produced such excellent results with almost identical sensitivity which eliminates the need to add CAR components.

此共聚的合成為簡單且對環境友善的程序. 烘烤溫度介於150 - 180℃,對成膜的阻劑性質幾乎沒有影響.但是如果低至95℃則會降低對比度. 產品的科基係數為1.541 - 1.544. 顯影劑對阻劑的敏感度,解析度有相當程度的影響. 耐乾蝕刻性質類似於一般市售光阻,但比PMMA阻劑好2倍. CSAR阻劑具有高敏感度,高解析度及耐蝕刻特性,並可形成良好的懸浮剝離結構. CSAR有著化學放大型阻劑的優點,卻無需添加化學放大所需的成份與製程.

Reaction mechanism

By comparison with PMMA resists, CSAR 62 is characterized by a higher sensitivity and a significantly better plasma etch resistance. The main components of the resist are poly(α-methylstyrene-co-chloromethacrylic acid methyl ester), an acid generator and the safer solvent anisole. The higher sensitivity results from the addition of halogen atoms to the polymer chain. Generally, chlorine is used (this is true for CSAR 62 -chloromethacrylic acid methyl ester), but bromine or iodine would be an option as well. The chlorine atom facilitates the breaking of the polymer chain during the exposure with electrons. Besides that, there is the supporting effect of a halogenated acid generator. By adding further reactive halogens, the attack on the polymer chain is accelerated once more. Thus, less energy (smaller dose) is needed for the breakdown of the high-molecular polymer in small fragments. These fragments quickly dissolve in the developer, while the unexposed, still high-molecular resist areas remain intact.

相較於PMMA阻劑,CSAR有較高的敏感度及優異的耐蝕刻特性. CSAR 62主要成份是α-甲基苯乙烯與甲基丙烯酸甲酯共聚物,光酸及苯甲醚溶劑. 高敏感度特性主要來自於高分鏈接上鹵素原子,通常是氯原子,亦可使用溴或碘原子. 氯原子在電子束曝光時,辦演著斷鏈的角色,同時支援氯化光酸反應,促使連鎖反應.