Application of sputter etching treatment to the formation of semiconducting silicide film on Si substrate

Si基板へのシリサイド半導体薄膜作製におけるスパッタ・エッチ処理の適用

山口 憲司; 江坂 文孝  ; 笹瀬 雅人*; 山本 博之; 北條 喜一

Yamaguchi, Kenji; Esaka, Fumitaka; Sasase, Masato*; Yamamoto, Hiroyuki; Hojo, Kiichi

シリサイド半導体の代表格である-FeSiの薄膜をSi基板上に蒸着する際、蒸着前に低エネルギー(1keV)イオンによる基板のスパッタ・エッチ(SE)処理を行うことが有効である。筆者らはこの方法でSi(100)基板上に-FeSi(100)の高配向膜を作製することに成功している。また、透過型電子顕微鏡による断面観察や、放射光を用いたX線光電子分光法並びにX線吸収分光法による表面化学状態の観察により、973Kで成膜した-FeSi薄膜は均質性が高いものの、イオン照射に由来する欠陥を含んでいることを明らかにした。筆者らは、さらに欠陥の少ない薄膜を得るために、より低入射エネルギーでのSE処理を行い、0.8keV(Ne)まで入射エネルギーを下げても、従来の3keVでの処理と同程度の高配向性を有する-FeSi(100)薄膜が作製できることを示した。

"Semiconducting silicides", such as -FeSi, BaSi, MgSi, etc. are composed of elements which are non or less toxic and are naturally abundant, so that they are considered to be ecologically friendly. These materials are being investigated for applications in optoelectronics, photovoltaics, photonics, thermoelectrics, and so on. In order to fabricate silicide films on crystalline Si substrate, sputter-etching (SE) of the substrate with low energy ion beams has been successfully applied. When the conditions are met, a highly-oriented -FeSi (100) film can be grown on Si (100) substrate by means of ion beam sputter deposition method. According to cross-sectional transmission electron microscopy (TEM) observation, the interface of the SE-treated substrate and the film deposited at 973 K is smooth, although some defects are produced as a result of this treatment. On the other hand, a combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) revealed that relatively homogeneous -FeSi surface is formed at this temperature. In order to further improve the film properties with smaller amount of defects, SE-treatment is performed with the ions whose incident energy is below 1 keV. X-ray diffraction (XRD) analysis confirmed that highly-oriented -FeSi (100) film can be also obtained with SE-treatment by 0.8 keV Ne ions, as in the case of 3.0 keV Ne.