摘要
为了获得薄膜材料吸收率与深紫外激光照射能量密度间的对应关系,掌握薄膜材料深紫外吸收特性,应制定相应的吸收测量规范。介绍了激光量热法的原理及测试流程,分析了测试过程中的剂量效应、非线性吸收和不可恢复吸收等现象,提出了利用激光量热法测量应用于波长193nm紫外光刻系统的氟化物薄膜材料吸收率的方法,并进行了实际测量。根据所建立的测量方法,获得熔石英基底材料在193nm紫外光照射下的剂量效应及出现不可恢复吸收现象时相应的激光能量密度,进而测量出基底材料吸收率与激光能量密度之间的关系;通过热蒸发对基底镀氟化镁及氟化镧单层膜,测量镀膜后样品的吸收率与激光能量密度的关系,通过与镀膜前吸收率的对比,计算了两种薄膜材料吸收率与激光能量密度的关系,推算出薄膜材料在实际工作状态时的吸收率,并得到不同沉积温度下氟化镧薄膜材料吸收率、粗糙度与波纹度。实验结果证实了新提出测量方法的可行性,测量结果为改善系统成像质量以及延长元件使用寿命提供支持。
To obtain the relationship between the absorptances of thin-film materials and the incoming ultraviolet laser energy density, it is better to establish a standard measurement method. The principle and measurement process of laser calorimetry is introduced, the dose depending effect, nonlinear absorption, and unrecoverable absorption phenomenon that might influence the measurement results are analyzed, a method based on the laser calorimetry is proposed, which is used to measure the absorptance of fluoride coatings that can be used in 193 nm ultraviolet photolithography systems, and experiments. According to the new proposed method, the dose depending effect, the corresponding laser energy density while the unrecoverable absorption phenomenon appears when the fused silica substrates are irradiated by 193 nm laser are measured; the relationship between absorptances of substrates and the laser energy density are calculated. After that, two substrates are coated with LaFa and MgF2 separately by boat evaporation; the relationships between absorptances of the coated samples and laser energy density are measured. By the comparison of absorptances before and after coating, the relationships of the two thin-film materials between absorptances and laser energy densities are calculated, and the absorptances of LaF3 and MgF2 in actual working condition are figured out, also the relationship between deposited temperature and absorptance,roughness, waviness of LaFa is obtained. The experimental results confirm the feasibility of the proposed method, which help to improve the imaging quality and prolong the working life of the objective system that can be used in the photolithography system.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2014年第8期180-187,共8页
Chinese Journal of Lasers
基金
国家重大科技专项02专题(2009ZX02205)
