碳化矽閘極氧化層在不同隔離結構下的可靠度特性

Reliability Characterization of SiC Gate Oxide in Different Isolation Structures

王韻茹(Yun-Ju Wang)

指導教授 ： 簡昭欣 ； 林育賢

國立交通大學/國際半導體產業學院/國際半導體產業學院/碩士(2019年)

摘要

為了更有效率的使用能源，近來功率元件在材料的選取上轉向使用寬能隙半導體。過去因為寬能隙半導體的製程不夠成熟與成本過高的關係，多使用矽做為功率元件的材料，但由於寬能隙的材料可以有效的降低功率元件的功率耗損，所以寬能隙材料成為功率元件的研究主軸。然而在眾多寬能隙材料中，碳化矽不僅擁有高崩潰電壓、良好的熱傳導能力以及在製程中跟傳統的矽有較多的相似之處等優勢，因此碳化矽非常適合做為功率元件的材料。但是因為碳化矽本身鍵結很強的關係，其氧化速率遠低於傳統的矽。因此需要在足夠高溫的環境下才能有效的在碳化矽表面生長氧化層。在長氧化層的同時我們必須顧慮到碳化矽與氧化層界面的缺陷密度，如何有效的降低其界面缺陷密度也是此篇論文的目標。
我們分別比較了LPCVD與LOCOSiC兩種隔離結構對於可靠度的影響，但是量測出的LOCOSiC可靠度與崩潰電壓都比LPCVD還要差，我們懷疑這是因為氮化物層的關係導致碳化矽被破壞到。因為在過去的實驗中LOCOSiC的製作過程使用了矽氧化物層而不是氮氧化層，當時量測到的崩潰電壓LOCOSiC是大於LPCVD的。又因為從TEM圖中可以看到碳化矽崩潰後再LOCOSiC中的破壞程度比LPCVD中的破壞程度還要大。因此我們也針對阻擋層的的材料與製程步驟探討了可能的解決方案。

關鍵字

碳化矽 ； 氧化層可靠度 ； 氮氣鈍化

並列摘要

In order to use energy more efficiently, power devices have recently turned to wide bandgap semiconductor in material selection. In the past, because the process of wide bandgap semiconductors was not mature enough and the cost were too high, silicon was utilized as the material of the power device. However, the wide bandgap materials can effectively reduce the power consumption of the power device. According to this reason, the wide bandgap materials have become the main materials of the power device. In many wide bandgap materials, silicon carbide has advantages such as high breakdown voltage, high thermal conductivity and the fabrication is similar with the traditional silicon. Therefore, silicon carbide is very suitable as the materials of power devices. Nevertheless, the bonding between silicon and carbon is very strong, the oxidation rate is much slower than that of the silicon substrate. Therefore, it is necessary to effectively grow the oxide layer on the surface of silicon carbide in a sufficiently high oxidation temperature environment. In additional, to effectively reduce the density of interface state is another goal of this study.
We compared the effects of LPCVD and LOCOSiC isolation structures on reliability. The result shows that the reliability and breakdown voltage of LOCOSiC isolation structures are worse than LPCVD isolation structures. We suspect that the stress of the nitride layer causes the silicon carbide to be destroyed. Base on pervious results done by our group, the hard mask used in the LOCOSiC isolation structures were SiO2 instead of nitride layer. The breakdown voltage of LOCOSiC isolation structures were higher than LPCVD isolation structures in previous experiment. On the other hand, the TEM image shows the of damage of the LOCOSiC split is more serious than that of the LPCVD split. The potential solutions are also described as references toward future work.

並列關鍵字

SiC ； oxide reliability ； NO passivation

參考文獻

References

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