Addressing challenges in lithography using sub-millisecond post exposure bake of chemically amplified resists
Addressing challenges in lithography using sub-millisecond post exposure bake of chemically amplified resists
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使用化学放大抗蚀剂的亚毫秒曝光后烘烤解决光刻挑战
DOI：
10.1117/12.879288
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M. Chandhok
中科院分区：
文献类型：
--
作者：
B. Jung;C. Ober;M. Thompson;T. Younkin;M. Chandhok
化学放大的光刻胶需要曝光后烘烤（PEB），通常在90-150°C的热板上烘烤30-120秒，以催化聚合物骨架的去保护。在PEB过程中，光产生的酸的过度扩散导致线边缘清晰度的丧失，潜在图像的模糊和线边缘粗糙度的变化。酸扩散和脱保护都是热激活过程，其相对速率受PEB的时间/温度分布的影响。在这项工作中，我们介绍了一种替代的PEB方法，涉及使用连续波CO2激光器在300°C至420°C的温度范围内进行毫秒时间框架加热。建立了一种表征激光PEB （l-PEB）下耐蚀脱保护和酸扩散动力学的方法，并与传统热板PEB进行了比较。结果表明，与热板PEB相比，l-PEB的脱保护率随温度的敏感性较小，表明脱保护机制可能发生了变化。与从热板PEB数据推断的值相比，l-PEB下的酸扩散系数降低了102-103倍。在EUV照射下，使用l-PEB形成的图案显示出明显更光滑的表面粗糙度，而所需剂量不到热板PEB所需剂量的一半，这是在高PEB温度下增强脱保护和在毫秒时间内减少酸扩散的直接结果。
Chemically amplified photoresists require a post exposure bake (PEB), typically on a hot plate at 90-150°C for 30-120 seconds, to catalytically deprotect the polymer backbone. During PEB, excessive diffusion of the photo-generated acid results in loss of line edge definition, blurring of latent images and changes in the line edge roughness. Both acid diffusion and deprotection are thermally activated processes, with the relative rates affected by the time/temperature profile of the PEB. In this work, we introduce an alternate PEB method involving millisecond time frame heating over a temperature range of 300°C to 420°C using a continuous wave CO2 laser. A methodology is developed for characterizing the resist deprotection and acid diffusion kinetics under laser PEB (l-PEB) and comparing the behavior with conventional hot plate PEB. Results show that the deprotection rate sensitivity with temperature is smaller for l-PEB compared to that of hot plate PEB, suggesting a possible change in the deprotection mechanism. Acid diffusivity under l-PEB is reduced by a factor of 102-103 compared to values extrapolated from the hot plate PEB data. Under EUV exposure, patterns formed using l-PEB show significantly smoother surface roughness while requiring less than half the dose required for hot plate PEB - a direct consequence of enhanced deprotection at high PEB temperature and reduced acid diffusion in the millisecond time frame.