Electrical Analysis and Investigation with Dynamic Negative and Positive Bias Stress of Hf1-xZrXO2/Metal Gate for P-MOSFETs
Sze, Simon M.
|關鍵字:||Hf1-xZrXO2;動態負偏壓;動態正偏壓;閘極電流;Hf1-xZrXO2;Dynamic Negative Bias Stress;Dynamic Positive Bias Stress;Gate Current|
|摘要:||在本論文中，藉由不同量測方法(DC Id-Vg, charge pumping)發現隨著p-MOSFETs金屬閘極中的鋯含量增加，臨界電壓顯著的下降、載子遷移率上升、汲極電流上升，此為摻入鋯能讓介電常數上升以及降低結晶粒度尺寸。在動態負偏壓後量測次臨界擺幅以及GIDL(Gate Induced Drain Leakage)電流知道是電洞注入到Bulk造成臨界電壓上升與載子遷移率下降。我們利用分流法判別出閘極漏電是電洞經由通道流向閘極端所貢獻，而非電子從閘極流向通道。我們也發現閘極漏電流是由Frenkel-poole及tunneling兩種電流串聯所貢獻。在Vg<VT下，隨著電場加大，閘極漏電由Frenkel-poole主導轉為tunneling主導；Vg>VT下，隨著電場加大，閘極漏電由tunneling主導轉為Frenkel-poole主導。進而得知閘極電流的峰產生條件是Frenkel-poole>tunneling。接著比較摻入鋯的有無，發現摻入鋯的元件能讓閘極漏電變小，進而抑制Frenkel-poole路徑。施加動態正偏壓後，電子由基板流往閘極端過程中產生介面缺陷以及主體缺陷。在DC量測基本電性下主體缺陷的電子會進行補償造成實際量測到的起始電壓飄移比電荷幫浦量到的起始電壓飄移還要小。|
The electrical characteristics and reliability of Hf1-xZrxO2 gate metal-oxide- semiconductor field effect transistors (MOSFETs) are investigated by analyzing experimental data from DC Id-Vg , and charge pumping measurements. We have found that higher mobility(μ), lower threshold voltage (Vth), and improved charge trapping without a significant increase in leakage current can be obtained when we increase the Zirconium content in metal gate for p-MOSFETs. This is because ZrO2 can stabilize the tetragonal phase and enhance the κ value in Hf1-xZrxO2 devices. Because of the increased VT and GIDL, we believe that hole trapping is the dominate effect under AC dynamic NBS. The gate current is found to be holes going from the channel to the gate, not electrons going from the gate to the channel. In addition, the gate leakage current is due to a series of Frenkel-Poole and tunneling current. Under Vg<VT condition, with the electric field increased, the gate leakage of Frenkel-Poole to tunneling dominant, moreover under Vg>VT condition, with the electric field increased, the gate leakage of tunneling to Frenkel-Poole dominant. And then learned that the gate current hump conditions of Frenkel-Poole>tunneling. Finally, the reliability analysis the incorporation of Zirconium or absence of components in p-MOSFETs allows the incorporation of Zirconium gate leakage become smaller, and thus inhibition of Frenkel-Poole. Afetr dynamic PBS, electrons from the substrate flow to the gate; meanwhile, cause the interface traps and the bulk traps. In the DC measurement, the bulk trap of the electron compensate for the actual measured, therefore its threshold voltage shift than the charge pumping measured threshold voltage shift is much smaller.
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