集成电路产业蓬勃发展，光刻技术日新月异，随着曝光波长的减小，图形分辨率越来越高，但同时反射光线对分辨率的影响也越来越显著。光刻胶用抗反射涂层根据使用的位置不同可以分为底部抗反射涂层(Bottom Anti-Reflective Coating, BARC）和顶部抗反射涂层（Top Anti-Reflective Coating，TARC）。对光刻胶成像影响最大的是来自基底的反射光，其在光刻胶内部穿梭会造成多重曝光和驻波效应，使得光刻胶侧壁呈现锯齿状。使用BARC可以大大抑制基底反射光，与TARC相比，BARC对光刻胶形貌的改善效果更佳。本文设计合成了两种抗反射涂层紫外吸收剂，并研发出相应BARC组合物。后续又对制备的抗反射涂层进行了一系列测试，探究其对改善光刻图形方面的性能表现。

我们所设计制备的第一种紫外吸收剂是含有二苯甲酮结构的聚对羟基苯乙烯衍生物，应用于248-nm光刻的底部抗反射涂层。首先尝试将带有一系列取代基的苯甲酰氯与PHS进行傅-克反应，但是酚羟基的存在会使催化剂失活。因此改为在碱存在下将苯甲酰氯与聚对-羟基苯乙烯进行反应得到酯化产物，再将该酯化物进行重排反应，得到含有二苯甲酮基团的聚对-羟基苯乙烯衍生物。通过傅里叶红外光谱（FT-IR）、核磁共振氢谱（¹H NMR）对所得的聚合物结构进行了表征。通过紫外光谱（UV）、差示扫描量热法（DSC）、热重分析（TGA）等方法对聚合物的性质进行了表征。由这种含有二苯甲酮结构的聚对-羟基苯乙烯衍生物和交联剂、溶剂等组成了适用于248-nm光刻的BARC材料。这种BARC可在硅片表面形成非常均匀的薄膜。200 ℃左右热固化后，在光刻胶常用溶剂与稀碱水显影液中均不溶。将上述的BARC配合商品248-nm正性光刻胶，采用KrF激光光刻设备进行光刻实验评价，成像结果表明BARC能有效的消除驻波效应和多重曝光造成的锯齿状缺陷，使所得图形线条侧壁光滑。

我们设计制备的第二种紫外吸收剂是含有2,6-二亚苄基环己酮结构的多酚聚合物，先通过环己酮与芳香醛进行醛酮缩合，再进行酚醛化反应得到聚合物。通过紫外光谱（UV）、红外光谱（FT-IR）、差示扫描量热法（DSC）、热重分析（TGA）等方法对聚合物的性质进行了表征。其紫外吸收扩展到400 nm，因此可应用于i-线光刻和248-nm光刻使用的BARC材料。由这种多酚聚合物紫外吸收剂和交联剂、溶剂等组成的BARC材料。将这种BARC配合商品i-线正性光刻胶，采用i-线步进光刻机进行光刻实验，成像结果表明这种BARC能有效的消除驻波效应和多重曝光造成的锯齿状缺陷，使所得成像图形线条侧壁光滑。

传统的BARC在完成光刻后需要使用等离子刻蚀的方法去除，工艺复杂，成本较高，还容易对基材造成损伤。针对这些缺点，研究者提出了可显影底部抗反射涂层（Developable BARC），其可以在曝光后的显影过程中与光刻胶一同溶解于显影液中去除。在包含有第二种紫外吸收剂的BARC材料的基础上设计了一种DBARC材料。在实验室中，配合自制的i-线正性光刻胶进行了初步的成像实验，所得图案分辨率较高且显影干净，无光刻胶和DBARC残留。

The integrated circuit industry is booming, and the lithography technology is changing with each passing day. With the decrease of exposure wavelength, the graphics resolution is getting higher and higher, but at the same time, the influence of reflected light is becoming more and more significant. The anti-reflective coating for photoresist can be divided into bottom anti-reflective coating (BARC) and top anti-reflective coating (TARC) according to the position of usage. The most harmful effect on photoresist imaging is the reflected light from the substrate, which will cause multiple exposure and standing wave effect when shuttling inside the photoresist film, making the photoresist pattern sidewall serrated. BARC can greatly suppress the effect of the reflected light from the substrate. Compared with TARC, BARC can take better effect on the improvement of photoresist patterning. In this paper, two kinds of UV absorbers for anti-reflective coatings were designed and synthesized, and the corresponding BARC formulations were developed. Subsequently, a series of tests on the BARCs were conducted to explore their performance in improving photoresist patterning.

The first UV absorber we prepared  are poly (4-hydroxystyrene) derivatives containing benzophenone groups, which has strong absorption at 248 nm wavelength, and the BARCs formed by the UV light absorbers are applicable to the bottom anti-reflection coating for 248-nm photoresist. In this paper, benzophenone group was introduced into PHS to prepare BARC UV absorber. The structure of the product  was characterized by FT-IR and 1H NMR. The properties of the polymer were characterized by ultraviolet spectroscopy (UV), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and ellipsometry. Subsequently, BARC formulation was developed, which was composed of the poly (4-hydroxystyrene) derivative containing benzophenone groups, crosslinking agent and solvent. This BARC can form uniform films on the surface of silicon wafer. After thermal curing at around 200 ℃, it became insoluble in common solvents and developer for photoresist. The above BARC combined with commercial 248-nm positive photoresist is evaluated by using KrF laser lithography equipment. The imaging results show that the BARC can effectively eliminate the sawtooth defects caused by bottom reflected light, and make the sidewall smooth.

The second UV absorber we prepared is a polyphenol polymer containing 2,6-dibenzylidene cyclohexanone groups in the main chain. It was prepared by aldol condensation of cyclohexanone and aromatic aldehyde and then by phenolic condensation reaction with formaldehyde. The properties of the polymer were characterized by UV, FT-IR，DSC, TGA and ellipsometry. The UV absorption of the polyphenolic polymer is expanded to 400 nm and can be used to form BARC material both for i-line photolithography and 248-nm photolithography. BARC material can be formulated with this polyphenol polymer, crosslinking agent, solvent, etc. The BARC is evaluated together with commercial i-line positive photoresist using i-line stepper. The imaging results show that the BARC can effectively eliminate the sawtooth defects caused by bottom reflected light, and make the sidewall of the pattern smooth.

The traditional BARC needs to be removed by plasma etching, which is a complex process and with high cost. Considering these shortcomings, researchers try to develop bottom anti-reflective coating for photoresist, which can be dissolved in the developer together with photoresists during the development process after exposure. A kind of DBARC was designed and prepared based on previous BARC containing the second UV absorber.  In our laboratory, preliminary exposure experiments for the DBARC together with self-made positive i-line photoresist was conducted, and clean patterns with high resolution were obtained without residue from both the photoresist and DBARC.