Development of new fluoride single crystals as VUV window materials for next-generation optical lighography

开发新型氟化物单晶作为下一代光学光刻的 VUV 窗口材料

基本信息

批准号：
12555001
负责人：
FUKUDA Tsuguo
金额：
$ 8.64万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555001/
关键词：
LiCaAlF_6 KMeF_3 BaLiF_3 F_2laser Optical lithography Window material VUV Single crystal

项目摘要

In order to develop new fluoride single crystal materials as window materials for next-generation optical lithography, especially for F_2 laser with 157 nm, crystal growth and VUV optical characterization have been done for different fluorides. Among them, LiCaAlF_6, KMgF_3, BaLiF_3, and Sr:BaF_2 were focused in this work. The advantage of LiCaAlF_6 was its high transparency until 112 nm. Detailed refractive index measurement down to 5 decimal points also showed that the birefringence diminish at 152 nm which is very close to the wavelength of F_2 laser. The advantages of other three crystals were their cubic structure, which enables 0 birefringence, and high transparency as well. Successful growth of LiCaAlF_6, KMgF_3, and BaLiF_3 single crystals with 2 inches in diameter showed that these crystals have possibility to be grown with larger diameter. Especially, 4-inch diameter LiCaAlF_6 single crystal was successfully grown by the Czochralski technique to show the real possibility of diameter extension. For further investigation to extend the diameter, the Bridgman technique was used. KMgF_3 crystal with 10 cm in diameter was grown, although it contained white milky material. Transparent LiCaAlF_6 crystals with 6-inch diameter were grown by the insertion of several plates inside a crucible. The insertion of plates was effective to separate transparent crystal and white material which contained impurity phases. Damage resistance of grown crystals were investigated. Total damage obtained after high power X-ray radiation showed that LiCaAlF_6 and Sr:BaF_2 have very high resistance. These two crystals also showed almost no damage formation after F_2 laser irradiation with 10 times high power than that is used in a practical optical lithography.

为了开发新的氟化物单晶材料作为下一代光刻的窗户材料，尤其是对于具有157 nm的F_2激光器，已经为不同的氟化物进行了晶体生长和VUV光学表征。其中，LICAALF_6，KMGF_3，BALIF_3和SR：BAF_2专注于这项工作。 LICAALF_6的优势是其高透明度，直到112 nm。详细的折射率测量值降低到5个小数点，还表明，双重折线在152 nm处减小，这非常接近F_2激光的波长。其他三个晶体的优点是它们的立方结构，它可以使0个双折射和高透明度。直径2英寸的LICAALF_6，KMGF_3和BALIF_3单晶的成功生长表明，这些晶体有可能以较大的直径生长。尤其是，Czochralski技术成功地生长了直径4英寸LICAALF_6单晶，以显示直径延伸的实际可能性。为了进一步研究以扩展直径，使用了Bridgman技术。 kMGF_3直径为10厘米的晶体虽然含有白色乳白色材料，但仍有直径为10 cm。透明的LiCaalf_6晶体的直径为6英寸，通过在坩埚中插入几个板的生长。板的插入可有效分离包含杂质相的透明晶体和白色物质。研究了生长晶体的损伤。高功率X射线辐射后获得的总损害表明LICAALF_6和SR：BAF_2具有很高的电阻。这两个晶体在F_2激光照射后几乎没有损伤形成，其功率高10倍，而不是在实用光刻中使用的损伤。