基于真空紫外光表面活化的硅基晶圆低温直接键合研究

发布时间：2018-03-23 06:07

  本文选题：低温键合　切入点：硅基材料　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来集成电路器件的特征尺寸日益接近摩尔定律的物理极限,电子/光学/生物医疗器件的多功能芯片集成变为新型电子产品的关键推动力。键合(又称为“连接”)工艺是整合多元化复杂系统的不可替代的重要环节。晶圆直接键合可以使得经过抛光的半导体晶圆在不使用粘结剂的情况下结合在一起,在集成电路制造、微机电系统(MEMS)封装和多功能芯片集成等领域发挥着关键的作用。对于传统的直接键合由于引入高温,引起热应力以及热应变等问题。等离子体法以及超高真空键合方法等虽然实现低温键合,但是具有对材料表面损伤大,键合设备昂贵等不足。因此亟待开发出一种低成本、简单易行、键合缺陷少、绿色环保的低温晶圆键合方法。本文提出一种基于真空紫外光(VUV)表面活化的硅基晶圆低温直接键合方法,开发出实现真空紫外光活化晶圆表面实现低温直接键合的装置,选取光照时间,环境湿度,退火温度作为工艺参数变量,有效键合面积和键合强度作为评价键合质量的依据,最终得到实现硅/石英玻璃,石英玻璃/石英玻璃的低温直接键合的最佳工艺参数;进而结合真空紫外光对材料表面影响的分析结果和对键合界面的表征结果建立键合机理模型。研究结果表明:开发出的真空紫外光活化晶圆表面键合装置具有臭氧消除功能和光照气氛控制功能。在工艺参数为VUV光照时间15min,键合气氛相对湿度30%~40%,阶梯式退火方式,最高退火温度为200℃条件下,可实现非洁净间环境下硅基晶圆直接键合。硅/石英玻璃键合下有效键合面积高达90%以上,退火后键合界面强度高于基体抗弯强度。石英玻璃/石英玻璃键合下有效键合面积接近100%,退火后键合接头强度达到6MPa,同时保持良好的透光率。对硅/石英玻璃,石英玻璃/石英玻璃键合界面进行TEM分析得出,键合界面连续无孔隙,实现了原子间连接。通过对光照前后材料表面变化分析,得出极短波长的真空紫外光(172 nm)可以有效去除硅基晶圆表面污染物,使材料表面Si-OH增多,提高表面活性。与此同时,进一步分析真空紫外光照射气氛所引入水蒸气的作用,得出适量水蒸气,可以提供大量自由羟基基团,同时在待键合界面通过氢键连接形成“水桥”实现室温键合。基于真空紫外光对材料表面的相互作用以及水应力腐蚀理论,建立了应用真空紫外光处理硅基晶圆表面低温直接键合模型。室温键合阶段,待键合界面间形成通过水桥进行连接,键合间隙由水分子填充,此阶段范德华力和氢键作为界面间主要吸引力实现预键合;退火过程阶段,键合界面间发生脱水反应生成大量共价键,处于间隙部位的水分子,一部分会沿着界面进行扩散平整表面,一部分向基体发生扩散使表层软化,键合孔隙逐渐消失,最终实现高强度键合。
[Abstract]:In recent years, the characteristic size of integrated circuit devices is closer to the physical limit of Moore's law. The multifunctional chip integration of electronic / optical / biomedical devices has become a key driving force for new electronic products. Bonding (also known as "connection") process is an irreplaceable and important part of the integration of complex and diverse systems. Wafers. Direct bonding allows polished semiconductor wafers to be bonded together without the use of binders, It plays a key role in IC manufacturing, MEMS packaging and multifunctional chip integration. Although the plasma method and the ultra-high vacuum bonding method realize the low temperature bonding, they have many disadvantages, such as large damage to the material surface, expensive bonding equipment and so on. Therefore, it is urgent to develop a kind of low cost. This paper presents a low temperature direct bonding method for silicon wafers based on the surface activation of vacuum ultraviolet light (VUV). A device for realizing direct bonding at low temperature on the surface of a wafer by vacuum ultraviolet light was developed. The parameters such as illumination time, ambient humidity, annealing temperature were selected as parameters, and the effective bonding area and bonding strength were used as the basis for the evaluation of bonding quality. Finally, the optimum process parameters for direct bonding of silicon / quartz glass and quartz glass and quartz glass at low temperature are obtained. Furthermore, a bonding mechanism model was established based on the results of the analysis of the effect of vacuum ultraviolet light on the surface of the material and the characterization of the bonding interface. The results show that the vacuum ultraviolet light activated wafer surface bonding device has the odor. Oxygen elimination function and illumination atmosphere control function. When the process parameters are VUV illumination time 15 minutes, the bonding atmosphere relative humidity 30 and 40, step annealing, Under the maximum annealing temperature of 200 鈩，

本文编号：1652206