硅通孔热应力对于器件性能的影响的研究

发布时间：2018-04-16 17:31

本文选题：TSV + 热应力　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：在二维集成电路中,互连金属层的增加限制了电路的性能。而利用垂直互连技术来实现多层芯片堆叠的三维集成电路(Three-Dimension-Integrated-Circuit,3D IC)在很多方面都就有优势,主要包括:缩短互连线的长度、降低功耗以及允许异质集成等等。实现垂直互连的最有效的方式是硅通孔(Through-Silicon-Via,TSV)技术,但TSV结构会引入许多问题,尤其在热机械可靠性方面。同时,TSV引起的热应力问题又会造成器件性能的变化。因此本文主要讨论了TSV热应力对于载流子迁移率、器件阈值电压以及饱和电流变化的影响,并得到了以下结论:(1)创建了提取TSV热应力的数学模型。利用弹性力学基本理论,尤其是平面应变问题以及平面轴对称结构问题,然后利用具体的TSV结构列出求解未知系数的边界条件,从而创建了提取TSV热应力的数学模型。(2)利用多种类型的TSV来进行验证。本文针对多种类型的TSV结构进行仿真,即传统的圆柱形TSV结构、环形TSV结构以及较为复杂的同轴TSV结构。把从热应力模型中得到的应力数据与仿真得到的应力数据放在同一个坐标系中进行验证,并对验证过的应力进行坐标系的转换。(3)不同沟道下的载流子迁移率的变化。本文讨论了不同沟道方向条件下的迁移率的变化情况,即[100]晶向和[110]晶向。当沟道方向为[100]晶向时,电子迁移率变化较大。而且在坐标轴方向变化较大,在两条坐标轴之间的区域变化较小。但当沟道方向为[110]晶向时,空穴迁移率变化较大。而且在两条坐标轴之间的区域变化较大,在坐标轴方向变化较小。同时根据相应的载流子迁移率变化情况,对器件的放置方式进行了讨论。(4)器件阈值电压的变化。TSV热应力还会引起器件阈值电压的变化,TSV热应力会使得器件阈值电压降低。其中P型金属氧化物半导体(P-Type-Metal-Oxide-Semiconductor,NMOS)器件的阈值电压最大减少量为32mV,N型金属氧化物半导体(N-Type-Metal-Oxide-Semiconductor,PMOS)器件的阈值电压最大减少量为50mV。(5)器件饱和电流的变化。TSV引起的热应力会造成器件载流子迁移率和器件阈值电压的变化,进而会引起器件饱和电流的影响。NMOS器件的饱和电流在整个坐标系均为增加的,并且最大的变化率超过了14%。同时NMOS器件的饱和电流在X轴方向增加较多,在Y轴方向上变化较小,这与只考虑迁移率变化的情况不同。PMOS器件的饱和电流变化更大,而且饱和电流在Y轴方向上增加较大,在X轴方向上减少。(6)TSV物理参数的影响。TSV结构的物理参数也会对器件的饱和电流产生影响,其中较小的TSV半径以及较大的绝缘层厚度可以对器件饱和电流的变化产生积极的作用。而且金属Cu和SiO2材料的组合下的饱和电流变化最大,接着是金属Cu和BCB材料的组合,然后是金属W和BCB材料的组合,最后是金属W和SiO2材料的组合。
[Abstract]:In two-dimensional integrated circuits, the increase of interconnect metal layers limits the circuit performance.Three-dimensional Integrated Circuit 3D ICs using vertical interconnection technology to realize multilayer chip stacking has advantages in many aspects, such as shortening the length of interconnection lines, reducing power consumption and allowing heterogeneous integration, and so on.The most effective way to realize vertical interconnection is the Through-Silicon-Viav technology, but the TSV structure will introduce many problems, especially in the aspect of thermal mechanical reliability.At the same time, the thermal stress caused by TSV will change the performance of the device.Therefore, the influence of TSV thermal stress on carrier mobility, device threshold voltage and saturation current is discussed in this paper, and the following conclusion is drawn: 1) A mathematical model for extracting TSV thermal stress is established.By using the basic theory of elasticity, especially the plane strain problem and the plane axisymmetric structure problem, the boundary conditions for solving the unknown coefficients are listed by using the concrete TSV structure.Thus a mathematical model for extracting TSV thermal stress is established. The model is verified by using various types of TSV.In this paper, many kinds of TSV structures are simulated, that is, the traditional cylindrical TSV structure, the ring TSV structure and the more complex coaxial TSV structure.The stress data obtained from the thermal stress model and the stress data obtained from the simulation are verified in the same coordinate system, and the verified stress is transformed into a coordinate system.In this paper, we discuss the change of mobility under different channel directions, that is, [100] direction and [110] direction.When the channel direction is [100], the electron mobility varies greatly.Moreover, there is a great change in the direction of the coordinate axis and a small change in the region between the two axes.However, when the channel direction is [110], the hole mobility varies greatly.Moreover, the region between the two axes varies greatly, and the change is small in the axis direction.At the same time, according to the change of carrier mobility, the device placement mode is discussed. The change of the threshold voltage. TSV thermal stress will also cause the change of the device threshold voltage. The TSV thermal stress will reduce the device threshold voltage.The maximum reduction of threshold voltage of P-Type-Metal-Oxide-Semiconductor NMOSs is the maximum reduction of the threshold voltage of 32mV / N type metal oxide semiconductor devices N-Type-Metal-Oxide-Semiconductor PMOSs. The maximum reduction of threshold voltage is 50mV.5. the thermal stress caused by TSV is caused by the change of saturation current.Changes in carrier mobility and threshold voltage of devices,The saturation current of NMOS devices is increased in the whole coordinate system, and the maximum change rate is more than 14.At the same time, the saturation current of the NMOS device increases more in the X axis direction and changes slightly in the Y axis direction, which is different from the case of considering the mobility change only. The saturation current of the NMOS device changes more greatly in the Y axis direction, and the saturation current increases greatly in the Y axis direction.The effect of the physical parameters of the. TSV structure on the saturation current of the device is also affected by decreasing the physical parameters in the X axis direction. The smaller TSV radius and the larger thickness of the insulation layer can have a positive effect on the change of the saturation current of the device.In addition, the saturation current of Cu and SiO2 is the largest, followed by the combination of metal Cu and BCB, then the combination of W and BCB, and finally the combination of metal W and SiO2.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386.1

【参考文献】