第四讲：衍射光栅及制作技术(3)

5.脉宽压缩光栅（PCG）脉宽压缩光栅的技术要求极高高线密度高衍射效率高损伤阈值大尺寸1480线/mm95%2J/cm2200mm×400mm脉宽压缩光栅的类型镀金光栅介质膜光栅介质镀膜光栅光栅结构镀金光栅介质镀膜光栅？介质膜光栅浮雕光栅基板高反膜层介质膜光栅参数设计htw光栅齿高h剩余厚度t占宽比=w/d高折射率材料:(nH,tH)低折射率材料:(nL,tL)HfO2,nH=1.91SiO2,nL=1.45对膜系的两种反射率的要求0.40.50.60.70.80.91.01.1Wavelength(m)0.00.20.40.60.81.0Reflectivity0.40.50.60.70.80.91.01.1Wavelength(m)0.00.20.40.60.81.0Reflectivity对于工作波长反射率尽可能高对于制作波长反射率尽可能低光栅截面形状的影响(HfO2在顶层)0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.190.190.190.290.290.290.380.380.380.480.480.480.580.580.580.670.670.770.770.860.860.960.96Power-sineGroove,30%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.100.100.190.190.190.290.290.290.380.380.380.480.480.580.580.670.670.770.770.860.860.960.96TrapezoidalGroove,30%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.100.100.190.190.290.290.380.380.480.480.580.580.670.670.770.770.770.860.860.960.96RectangularGroove,30%DutyCycle白区阈值：96%占宽比的影响0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.190.290.290.290.380.380.480.480.580.670.770.860.860.860.960.96TrapezoidalGroove,20%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.100.100.190.190.190.290.290.290.380.380.380.480.480.580.580.670.670.770.770.860.860.960.96TrapezoidalGroove,30%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.100.100.190.190.190.290.290.290.290.380.380.480.480.580.580.670.670.770.770.860.860.860.960.96TrapezoidalGroove,40%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.190.190.290.290.290.380.380.380.380.480.480.480.480.580.580.580.580.670.670.770.770.860.860.960.960.960.96TrapezoidalGroove,50%DutyCycle0.00.20.40.6ResidualThickness(m)0.00.20.40.6GrooveDepth(m)0.100.190.290.380.480.480.480.580.580.580.580.670.670.670.670.670.770.770.770.770.770.770.860.860.860.860.860.860.960.960.960.960.960.96TrapezoidalGroove,60%DutyCycle介质膜光栅制作工艺流程基板准备涂胶曝光显影离子束刻蚀清洁处理大口径全息曝光光学系统1480线/mmHfO2/SiO2多层介质膜扫描离子束刻蚀光刻胶掩模离子源离子束太阳光下拍摄的80mm×150mmPCG照片样品在同等曝光和刻蚀条件下的PCG槽形结构顶层为HfO2的多层介质膜光栅美国中国美国LLNL制作的多层介质膜光栅，尺寸150mm×355mm激光器M3M1M2L2L1P1L3DH2H1S2S1基片AD板计算机快门曝光监测曲线H3P激光器M3M1M2L2L1P1L3DH2H1S2S1基片AD板计算机快门曝光监测曲线H3P曝光实时监测系统YAG激光水泵AD板计算机LD激光D2D1基片显影监测曲线偏振棱镜显影实时监测系统abcd-0.10.00.10.20.30.40.50.60.70.802000400060008000Intensity(a.u.)Time(min.)db3YAGdb3LD显影终点判据理论曲线实验曲线长曝光正常曝光短曝光0.00.51.01.52.02.5050010001500200025003000Intensity(a.u.)Time(min.)eb190.00.51.01.52.02.502000400060008000Intensity(a.u.)Time(min.)eb30.00.20.40.60.81.01.21.4010002000300040005000Intensity(a.u.)Time(min.)eb50.00.51.01.52.02.502000400060008000Intensity(a.u.)Time(min.)db5YAGdb5LD0.000.040.080.120.160.200100020003000400050006000Intensity(a.u.)Time(min.)db19YAGdb19LD-0.10.00.10.20.30.40.50.60.70.802000400060008000Intensity(a.u.)Time(min.)db3YAGdb3LD占宽比28.6%占宽比27.5%占宽比26.8%实验1：曝光时间对掩模的影响0.00.20.40.60.81.01.2010002000300040005000Intensity(a.u.)Time(min.)db8YAGdb8LD-0.20.00.20.40.60.81.01.21.41.61.80100020003000400050006000Intensity(a.u.)Time(min.)eb825实验2胶厚变化对槽形的影响甩胶浓度从1:3改为1:2.5•胶厚改变后，实测显影曲线变化不大。说明这种方法对胶厚误差有宽容性•SEM结果：平均胶厚796nm，方差91nm。虽然厚度有所波动，但是用上述监测方法，都能得到露底和占宽比小于30%的掩模0.10.20.30.40.50.60.70200040006000800010000Intensity(a.u.)Time(min.)db14YAGdb14LD0.000.050.100.150.200500100015002000250030003500Intensity(a.u.)Time(min.)db15YAGdb15LD0.100.150.200.250.300.3505001000150020002500300035004000Intensiyt(a.u.)Time(min.)db16YAGdb16LD0.10.20.30.40.50.60200040006000800010000Intensity(a.u.)Time(min.)db17YAGdb17LD0.050.100.150.200.250.300.350.400.45010002000300040005000Intensity(a.u.)Time(min.)db18YAGdb18LD1417181615实验3：掩模槽形在显影过程中的演变•显影曲线中1.064m波长对应的衍射效率最后一个峰值到来意味着露底•之后的衍射效率降低意味着开始改变占宽比•按照这样的方式显影，当光刻胶露底时，占宽比已经小于35%。-0.10.00.10.20.30.40.50.60.70.8-5000500100015002000250030003500Intensity(a.u.)Time(min.)db2YAGdb2LD-0.20.00.20.40.60.81.01.21.41.60100020003000400050006000Intensity(a.u.)Time(min.)eb2其它实验结果光栅的拼接最新的光栅制作技术美国PGL（PlymouthGratingLaboratory）：扫描干涉光刻