不同高介電常數材料與奈米微晶粒非揮發性記憶體

Abstract

此論文利用數種高介電值材料做為捕陷電荷層、阻擋層，來取代傳統的氮化矽材料所形成之捕陷電荷層與二氧化矽材料所形成的阻擋層；並調變製程中的處理方式使得我們可以探討比較純以不同高介電值材料做為捕陷電荷層與不同高介電值材料所形成之奈米微晶粒做為捕陷電荷層的SONOS型非揮發性快閃記憶體。特別的是在於我們將高介電材料沉積於源極/汲極與穿隧層先製備完成 首先，我們利用二氧化鉿(HfO2)薄膜與鉿矽酸鹽(Hf-Silicate)薄膜做為捕陷電荷層所製成的SONOS型非揮發性快閃記憶體,其中兩者的穿遂層厚度皆為2nm；利用二氧化鉿(HfO2)薄膜所製成之記憶體元件由於具有較高的介電常數因而有較快速的寫入/抹除速度,但也因此在2nm厚的穿遂層上其儲存資料持久性上的表現較為弱勢；值得一提的是：無論是二氧化鉿(HfO2)薄膜或是鉿矽酸鹽(Hf-Silicate)薄膜在沉積之後沒有再經過任何高溫的處理，因此保留其最原始的特性並且在經過一萬次的寫入/抹除後的記憶窗口並沒有明顯改變,表示說兩者在介電層品質的表現上是相當令人期待的。 再者，我們將二氧化鉿(HfO2)奈米微晶粒與二氧化鍶(CeO2) 奈米微晶粒做為捕陷電荷層所製成的SONOS型非揮發性快閃記憶體相互比較；發現二氧化鍶奈米微晶粒快閃記憶體在整體表現上皆優於二氧化鉿奈米微晶粒快閃記憶體 接著，我們使用兩種高介電材料氧化鋁(Al2O3)與(HfAlOx)替代傳統二氧化矽氧化層做為上阻檔層並將兩者在捕陷電荷層上同時換上二氧化鉿(HfO2)薄膜；在操作上可以相當順利的利用F-N穿遂來執行寫入與抹除。最後，我們分別利用通道熱電子注入與能帶熱電洞穿遂方式來比較兩種高介電材料氧化鋁(Al2O3)與(HfAlOx)與傳統二氧化矽氧化層做為上阻檔層之快閃記憶體元件特性，也由於高介電材料擁有較高的介電常數使得整體表現上皆優於傳統氧化層做為上阻檔層之快閃記憶體元件。

In this thesis, we design various nonvolatile memories with several high-k material films as charge-trapping layers. The high-k layers replace the conventional silicon nitride trapping layer and silicon dioxide blocking layer in the SONOS structure. We modified the treatment during the process such that we can fabricate the nanocrystal flash memories. In particularly, we complete the source/drain and the tunnel oxide first. First, we present the SONOS-type flash memory that was fabricated using hafnium oxide (HfO2) film and hafnium silicate (HfSiOx) film as the trapping storage layer. The tunnel oxide are both 2nm. These HfO2 memories exhibit faster programming/erasing speeds due to the higher dielectric constant. Because of that the tunnel oxide is 2nm and higher field across the tunnel oxide in HfO2 case, the data retention of HfO2 case is worse than HfSiOx case. In particularly, no any high-temperature process is used in all deposited high-k film and these high-k memories depict unobvious window shift after 10K P/E cycles. Therefore, the quality of both high-k films are high potential for application. Then, we compare with the SONOS-type flash memories that was fabricated using hafnium oxide (HfO2) nanocrystals and CeO2 nanocrystals as trapping storage layer. We observe the CeO2 case depicts the better performance. Next, we use two high-k material films to replace the conventional SiO2 film as blocking layer and change the trapping storage layer with HfO2 film. We can use F-N program/ erase without a hitch by transferred the material. The high-k material include Al2O3 and HfAlOx case depicts the better performance due to its higher dielectric constant.