机械应力对双极晶体管β的影响研究

Study on the Effects of Mechanical Stress onβof Bipolar Transistors

在芯片制造工艺过程中,机械应力对纵向NPN管共射电流增益β有很大影响。通过对上方第二层铝开槽可使β值回升。在第一层铝与第二层铝间的IMD层中加入压应力Si3N4膜,尺寸最大的NPN管的β恢复正常,而其他尺寸的NPN、PNP管的β均有不同程度上升。应用能带理论分析了应力对双极晶体管β的影响机制。结果表明,体硅(100)晶面内的应力对纵向NPN和纵向PNP管的β均有很大影响,并通过实验得到了验证。

In chip manufacturing process,the mechanical stress has a great influence on common-emitter current gainβof vertical NPN.By slotting on metal 2,the value ofβrebounded.A compressive stress layer of Si3N4was added into the IMD between metal 1and metal 2,and theβof the largest NPN had returned to normal mode.At the same time,theβof the other size NPN and PNP still increased.The influence mechanism of stress was analyzed using energy band theory.The results showed that the stress in(100)crystal plane had a great influence on theβof the vertical NPN and vertical PNP,and it had been verified by experiments.