Abstract:

With the increasing demand for decreasing the size and introducing full-scale 3D integration in the semiconductor wafer manufacturing process, higher requirements are put forward for the residual adhesive and the adhesion-reducing performance of UV adhesion-reducing adhesive. In this paper, an acrylic copolymer (ABP-PSA) bonded with benzophenone (BP) photoinitiator was prepared by copolymerization of 4-acryloyloxy benzophenone (ABP) with conventional acrylate monomers. The results showed that the introduction of ABP increased the molecular weight of acrylate copolymer and reduced its glass transition temperature. Thus, its cohesion strength and peeling force increased firstly and then decreased with the increase of ABP content. When the weight content of ABP was 3%, the normal peel strength of ABP-PSA was the highest (9.9N/25mm), which was significantly higher than that of the ABP-free copolymer (6.2N/25mm). During UV irradiation, the BP group seized the tertiary hydrocarbon atom in the polymer side chain, which made the polymer chain self-crosslinked and the peeling strength was reduced to 3.8N/25mm. The adhesion-reducing rate was over 60%. A new UV adhesion-reducing adhesive was prepared by ABP-PSA and castor oil-based polyurethane acrylate prepolymer (CO-PUB-PETA) with heat/light dual curing functions. With the help of the network structure formed by the thermal curing reaction of the NCO group in CO-PUB-PETA and the hydroxyl group in ABP-PSA, the 180° peel strength of the UV adhesion-reducing adhesive before UV curing exceeded 25N/25mm and the photopolymerization function was endowed to the acrylic copolymer adhesive. After UV irradiation, the BP groups bonded to the copolymer chains initiated the photopolymerization of the acrylic copolymer and the reactive diluent, and self-crosslinking for polymer chains occurred, forming a dense fully cross-linked structured adhesive film. The 180° peel strength was reduced to 0.12N/25mm and the adhesion-reducing rate was over 99.5%. Furthermore, the amounts of residual adhesives were significantly reduced.

Key words: UV adhesion-reducing adhesive, castor oil-based polyurethane acrylate, benzophenone, self-crosslinking, residual adhesives

摘要：

随着半导体晶圆制造过程对缩小尺寸和引入全尺寸3D集成需求的高涨，对紫外光（UV）减黏胶固化后的残胶量和减黏性提出了更高要求。本文通过4-丙烯酰氧基二苯甲酮（ABP）与常规丙烯酸酯单体溶液共聚制备了键合二苯甲酮（BP）光引发剂的丙烯酸酯共聚物主胶（ABP-PSA）。结果表明，ABP的引入可提高丙烯酸酯共聚物的分子量，降低其玻璃化转变温度，使得其内聚强度和剥离力随ABP含量的增加呈先提高后降低的趋势。当ABP的质量分数为3%时，ABP-PSA的常态剥离强度最高（9.9N/25mm），明显高于不含ABP的共聚物（6.2N/25mm）。UV照射时，BP基团夺取侧链中叔碳氢原子，使聚合物链自交联，剥离强度降低至3.8N/25mm，减黏率超过60%。本文采用ABP-PSA与具有热/光双固化功能的蓖麻油基聚氨酯丙烯酸酯预聚物（CO-PUB-PETA）反应制备了UV减黏胶。借助CO-PUB-PETA中异氰酸酯基与ABP-PSA中羟基的热固化反应形成的网状结构，使得该减黏胶UV照射前的180°剥离强度可超过25N/25mm，同时赋予主胶光聚合功能。UV照射时，键合在主胶链上的BP，引发主胶与活性稀释剂光聚合的同时发生自交联，形成致密的全交联结构胶膜，180°剥离强度降至0.12N/25mm，减黏率超过99.5%，并显著降低了残胶量。

关键词: 紫外光减黏胶, 蓖麻油基聚氨酯丙烯酸酯, 二苯甲酮, 自交联, 残胶