针对PMOS应用的TiN金属栅功函数调节

PMOS管需要金属栅的功函数接近硅的价带边，所以寻找到合适的方法调节TiN的功函数使之正向移动是金属栅工程的重点，也是难点。本文详细研究了TiN金属栅的厚度，栅介质沉积后退火，氧引入，以及N含量变化对TiN功函数的影响。发现随着TiN的厚度变厚，功函数会正向移动，但是在某一个厚度会达到饱和，另外，在少量氧气氛围下的栅介质沉积后退火，也能使功函数正向移动，而在TiN中引入氧元素，以及增大N的含量都会使TiN的功函数正向漂移。以上所述方法都能有效的调节TiN的功函数来适应PMOS的需要。

Modulation of the effective work function of the TiN metal gate for PMOS application

It is important to find a way to modulate the work function of the TiN metal gate towards the valence band edge of Si, which can meet the lower threshold voltage requirement of the p-type metal-oxide-semiconductor (MOS) transistor. In this work, the effects of TiN thickness, post-deposition annealing (PDA), oxygen incorporation and N concentration variation on the work function of the TiN metal gate in MOS structures are systematically investigated. It can be found that the work function positively shifts at the initial stage as the thickness of the TiN layer increases and stabilizes at such a thickness. PDA at N₂ ambience with O₂ trace can also cause a positive shift in the work function of the TiN metal gate. The same tendency can be observed when oxygen is incorporated into TiN. Finally, increasing the N concentration in TiN can also positively shift the work function. All these measures are effective in modulating the TiN metal gate so that it is more suitable for PMOS application.