光致抗蚀剂中实时监控由于环境光暴露引起的光刻胶膜的光谱灵敏度检测方案(白光干涉测厚)

Film Metrology & More...For further information please contact us at info@thetametrisis.com or sales@thetametrisis.comThetaMetrisis C 2016， www.thetametrisis.com ThetaMetrisis APPLICATION NOTE #016 Real-time monitoring of spectral sensitivity of a photoresist filmdue to ambient light exposure Goal： Accurate monitoring of transmittance changes of a photoresist film caused by ambient light exposure. lntroduction： In general， the spectral sensitivity of common photoresists ranges from the DUV to the shortwave VIS part of the spectrum. Without suited yellow/orange filters， artificial light as well as daylight willexpose substrates coated with photo resist layers within seconds thus making reproducible litho-processesimpossible. In our study， the standard room light exposure on a ~3um thick AZ5214 photoresist coated on amicroscope glass is investigated. Means & Methods： The photoresist was deposited on top of a microscope glass in a “safe lighting"conditionby using an orange filter， and then was stored into a dark container. An FR-pOrtable， operating in 370-1020nmspectral range， able to support transmittance measurements was ready to start measurements on a room withambient light. After the removal of the sample from the dark container， it was placed under the probe of FR-pOrtable which was monitoring the transmittance spectrum at real-time. Results： The recorded measurements are summarized in a plot (Figure 1) that illustrates the transmittancedata versus time in seconds. These results clearly suggest a) from the transmittance modulation in the >460nmspectral regime the AZ5214 thickness can be measured when considering the related refractive index values b)the photoresist film present high absorbance for the spectral regime <430nm which is the lithographicallyuseful spectral regime. The AZ5214 film thickness was measured to be 2.92um， Figure 2， in very goodagreement with independent stylus profilometry measurements. The decrease of absorbance vs. time in thestandard laboratory conditions is in agreement with the chemistry of AZ5214 (a mixture of mainly cresolnovolak and diazonaphthoquinone (DNQ)). At short exposure times the light is absorbed at a short distancefrom the film surface but as exposure continue the top part of the resist film bleaches， i.e. becoming UV-transparent， so while exposure continues， light is able to penetrate the whole film. As a consequence， theexposed resist film thickness goes approximately linear with the exposure dose. Figure 1： Transmission spectrum of the AZ5214 resist film after certain timeexposures to room light Figure 2： Thickness measurement of the AZ5214film in the spectral regime where the absorbance isnegligible Conclusions： The accurate real-time monitoring of exposed/unexposed transition through transmittancemeasurements of a photoresist due to ambient light using a FR-pOrtable was successfully demonstrated. Inaddition by the same measurements the photoresist film thickness was also measured by applying theinterference equations in the low-absorbance spectralrange. ( M. B olsen， “AZ 5200 Resists for P o sitive- and N e gative Patterning，"198 8 . ) ( MicroChemicals GmbH，“Exposure of Photoresists"， 2013 ) 实时监控由于环境光暴露引起的光刻胶膜的光谱灵敏度目标：准确监控环境光暴露导致的光致抗蚀剂膜的透射率变化。通常，普通光刻胶的光谱灵敏度范围从DUV到光谱的短波VIS部分。 如果没有合适的黄色/橙色滤光片，人造光和日光都会在几秒钟内使涂有光刻胶层的基材曝光，从而使可重复的光刻工艺变得不可能。 在我们的研究中，研究了在显微镜玻璃上涂覆的〜3μm厚的AZ5214光致抗蚀剂上的标准室内曝光量。使用橙色滤光片在“安全照明”条件下将光刻胶沉积在显微镜玻璃的顶部，然后存储在黑暗的容器中。 FR-pOrtable在370-1020nm的光谱范围内工作，能够支持透射率测量，可以在有环境光的房间开始测量。 从黑暗的容器中取出样品后，将其放在FR-pOrtable探针下，该探针可实时监测透射光谱。结果：记录的测量结果汇总在一个中，该图说明了透射率数据与时间的关系（以秒为单位）。这些结果清楚地表明：a）从> 460nm光谱范围内的透射率调制，当考虑相关的折射率值时，可以测量AZ5214的厚度b）光刻胶膜对<430nm光谱范围呈现高吸收性，这是光刻上有用的光谱范围。测得的AZ5214膜厚为2.92um，与独立的测针轮廓测量法非常吻合。在标准实验室条件下，吸光度随时间的降低与AZ5214（主要是甲酚酚醛清漆和重氮萘醌（DNQ）的混合物）的化学性质相符。在短的曝光时间，光在距膜表面很短的距离处被吸收，但是随着曝光的进行，抗蚀剂膜的顶部开始漂白，即变成紫外线透明的，因此在继续曝光的同时，光能够穿透整个膜。结果，曝光的抗蚀剂膜厚度与曝光剂量大致成线性关系。结论：通过使用FR-pOrtable成功地证明了通过环境光导致的光致抗蚀剂的透射率测量，可以对曝光/未曝光过渡进行准确的实时监控。 另外，通过相同的测量，还通过在低吸收光谱范围内应用干涉方程式来测量光致抗蚀剂膜的厚度。FR的工具基于白光反射光谱(Reports) 。准确同步的厚度测量及薄膜的折射率-一个广泛的多样化的应用范围广泛的光电特性的工具和整体解决方案，如:半导体、有机电子、聚合物、涂料和涂料、光伏、生物传感、化学传感...