氧分子對Si(111)-7x7表面碳化的影響

The effect of O2 molecules on the carbonization of Si(111)-7x7 surface

張宇翔(Yu-Hsiang Chang)

指導教授 ： 羅榮立

國立清華大學/理學院/物理學系/碩士(2020年)

摘要

隨著半導體與5G相關通訊產業的發展，半導體材料碳化矽(SiC)扮演重要的角色，為了突破元件體積的侷限與造成的負面影響，目前仍就是非常熱門的研究。論文中，我們是利用C2H4與C2H4+O2曝在Si(111)-7x7熱表面的碳化實驗，接著使用STM觀察其碳化表面。我們藉由改變溫度以及C2H4與O2的曝氣量，進而觀察反應產物的變化，像是一層原子深的凹陷(Crater)、二維結構以及三維的碳化矽顆粒(Grain)。從這些實驗結果，我們發現O2分子增強碳化產物的形成。這增強原因是由O2分子與表面Si原子發生放熱反應，生成揮發性氣體的SiO。我們碳化實驗的二維結構為((3^(1/2))x(3^(1/2)))R30度重構，其為其為Si(111)-7x7碳化表面起初的產物。最後，我們的觀察與文獻C2H2高溫STM實驗結果一致。

關鍵字

氧 ； 氧分子 ； 碳化 ； 矽(111)

並列摘要

With the development of the semiconductor and 5G-related communication industry, the semiconductor material silicon carbide (SiC) plays an important role. In order to break through the limitation of the component volume and the negative impact, silicon carbide is still a very hot research topic. In this thesis, by exposing C2H4 or (C2H4+O2) to hot Si(111)-7x7, we use scanning tunneling microscope (STM) to observe the carbonization of 7x7 surface. By changing the substrate temperature and the exposure of C2H4 and O2, we observe the changes of reacted products, like monolayer-deep craters, two-dimensional (2D) structures, and 3D grain. From these results, we found that O2 molecules enhance the creation of carbonization products. This enhancement is explained by the exothermic reaction of O2 molecules with surface Si atoms to yield volatile SiO. The 2D structure of carbonized surface in our results is conrmed to be a ((3^(1/2))x(3^(1/2)))R30度 reconstruction which is the initial product of carbonization on Si(111)-7x7 surface. This observation is consistent with the high temperature STM results of C2H2 in the literature.

並列關鍵字

Si(111) ； carbonization ； O2 molecules

參考文獻

[1] 周勇成，STM研究Si(111)表面的初始碳化，國立清華大學物理系，碩士論

文，中華民國108年

[2] P .Castrucci, A .Sgarlata, M .Scarselli, M .De Crescenzi, “STM study of acetylene reaction with Si(111): observation ofa carbon-induced Si(111) ((3^(1/2))x(3^(1/2)))R30度 reconstruction”, Surface Science 531, L329{L334, (2003)

[3] C. A. Pignedoli, A. Catellani, P. Castrucci, A. Sgarlata, M. Scarselli, M. De Crescenzi, and C. M. Bertoni, “Carbon induced restructuring of the Si(111) surface”, Phys. Rev. B 69, 113313, (2004)

[4] M. Scarselli, P. Castrucci, P.D. Szkutnik, A. Sgarlata, M. De Crescenz, “STM study of Si(1 1 1)7x7 reconstructed surface carbonization induced by acetylene”, Surface Science 559, 223-232, (2004)