鰭狀場效電晶體之二氧化鉿與二氧化矽介面電偶極子引致臨界電壓偏移之統計變異性模擬研究

Abstract

在高介電常數金屬閘極鰭狀場效電晶體中，電偶極子於二氧化鉿/二氧化矽介面的產生與擾動是一值得重視的課題，因此現象會造成奈米及半導體元件之臨界電壓偏移並對整體元件之良率有相當的衝擊。在此篇論文中，藉由現代三維電腦科技輔助軟體模擬的輔助，我們可以單獨對電偶極子於元件中造成的影響進行量測，以撇除其他製程擾動所形成之干擾因素，並針對電偶極子不同之擾動模式，如單一電偶極子位置變化或整體電偶極子大小擾動、整體電偶極子位置擾動對元件的影響進行統計模擬的實驗。除此之外，我們提出了一個統計公式來預測當一批鰭狀場效電晶體元件之二氧化鉿/二氧化矽介面中電偶極子個數為帕松分佈時，其臨界電壓變化的分布及標準差可由此公式快速預測，或可反推求得元件中電偶極子之濃度分布。在本模擬實驗中考慮了三種不同尺寸之元件，以了解隨著元件的微縮下，電偶極子對元件的影響趨勢會有怎樣的衝擊，並針對各尺寸之元件進行一定量之模擬研究，以取得具代表性之實驗數據。最後，我們降低電偶極子濃度來做模擬實驗，以驗證公式之預測值在低電偶極子濃度的狀況下是否也符合實驗預期。

The random HfO2/SiO2 interface dipole in high-k metal-gate fin field-effect transistor (HKMG FinFET) is one of the important topics in semiconductor manufacturing, concerning the threshold voltage variation, device reliability and yield rate. In this work, through the help of modern 3-D technology computer aided design (TCAD) software, we can focus on the impact of dipole effect in devices, decouple other variability sources while manufacturing processes. Also, we can perform simulation tasks with different random configurations of HfO2/SiO2 interface dipole, for example, single dipole with different positions, random size of HfO2/SiO2 interface dipole and random placement of HfO2/SiO2 interface dipole. In addition to the simulation tasks, we also propose a new analytic statistical model to predict the threshold voltage distribution and its standard deviation, under the condition of random number of HfO2/SiO2 interface dipoles in HKMG FinFET. In this simulation work, we consider three different device scales to investigate the trend of dipole effect under the scaling of HKMG FinFET devices. Moreover, we lower the dipole density to suppress the impact of HfO2/SiO2 interface dipole effect, and examine if the model still matches with our expectation under low dipole density condition.