利用升電壓測試法研究閘極氧化層之因時可靠度

Abstract

本論文提出了一個可靠性測試方法，我們稱之為“升電壓因時可靠度測試 法”。我們利用不同的基底、介電質材料、氧化層厚度與週邊，來評估此 方法應用於量產時之可重覆性。我們假設氧化層崩潰遵守對數─常態分佈 ，並且根據此假設來計算“電場加速因子”，再利用此參數來分析量測結 果，以證明此方法比定電場因時可靠度測試法更有效且快速。利用此方法 測所有的閘極介電質，都可以得到良好的重覆性。我們可以得到ONO、 薄 的SiO2以及N-Well上之SiO2有較穩定的可靠度的結論。最後，將此法所測 到的數據與定電場因時可靠度測試法的數據比較，我們發現它們是一致的 。所以本方法可以作為閘極介電質的測試方法。 The VRTDDB(Voltage-Ramping Time-Dependent-Dielectric- Breakdown),a reliability testing method for the gate dielectrics ,is proposed in this thesis. We used different bulks and dielec- tric materials,oxide thickness,peripheral conditions to evaluate the reproducibility of this testing method while it is applied in IC mass production. Provided that the oxide breakdown obeys the log-normal dis- tribution,the "electric field acceleration factor" is calculated. According to this parameter, this testing method is proved to be useful and faster than constant-field TDDB testing method. Using this proposed testing method, we can get high reproducibility for all kinds of gate dielectrics. We can also conclude that ONO, thinner SiO2 and SiO2 on N-Well have stable reliability. Finally, we compare the data measured by VRTDDB with that by TDDB, it is found that they are compatible. So, VRTDDB can be use as a testing method for gate dielectrics.