Atomic layer deposition of high-permittivity insulators from cyclopentadienyl-based precursors
Date
2010-10-26
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Abstract
Õhukeste ja kõrgekvaliteediliste ZrO2 ja HfO2 kilede kontrollitavat aatomkihtsadestust on võimalik realiseerida kasutades suhteliselt uudseid tsüklopentadienüülidepõhiseid metallide lähteaineid tavalistes laboratooriumitingimustes (mitte ilmtingimata puhasruumis). Tsirkooniumi ja hafniumi tsüklopentadienüülid, ehk sellised ühendid nagu (CpMe)2ZrMe2, (CpMe)2Zr(OMe)Me, (CpMe)Zr(NMe2)3, (CpEt)Zr(NMe2)3, (CpMe)2Hf(OMe)Me ja CpHf(NMe2)3 (Cp = C5H5, Me = CH3, ja Et = C2H5) osutusid koos hapniku lähteaine osooniga aatomkihtsadestusprotsessi jaoks sobivateks lähteaineteks. Antud lähteainekeemial põhineva sadestusprotsessi tulemusena oli võimalik saada tiheda struktuuriga dielektrilisi ja isoleerivaid metalloksiidkilesid pooljuhtivatel ja metallilistel substraatidel. Kasutades neid lähteaineid, oli võimalik saavutada ühtlane, s.t. konformaalne kasv ka kolmedimensionaalsetel substraatidel.
ZrO2 ja HfO2 kuubilise või tetragonaalse faasi stabiliseerimine järeltöötlustemperatuuri monokliinseks faasiks transformeeriva mõju vastu on osutunud probleemiks. Seetõttu stabiliseeriti neid faase dopeerides või kombineerides kilesid muldmetalloksiididega. HfO2 juhul kasutati hiljuti väljatöötatud ühte tsüklopentadienüüli ja kolme amino-gruppi sisaldavat lähteainet CpHf(NMe2)3 üttriumiga dopeeritud HfO2 kilede sadestamisel. ZrO2 puhul kasutati stabiliseerimiseks gadoliiniumi ja erbiumi oksiide, kusjuures ZrO2 ise kasvatati lähteainest (CpMe)2Zr(OMe)Me.
Selles töös uuritud sadestusprotsessid ja sadestatud kilede kvaliteet lubavad arvestada uuritud materjalidega paremate mälukondensaatorite väljatöötamisel.
Well-controlled atomic layer deposition (ALD) of high-quality thin films of ZrO2 and HfO2 can be realized using novel cyclopentadienyl-based precursors in normal laboratory conditions. Cyclopentadienyls of zirconium and hafnium, viz. (CpMe)2ZrMe2, (CpMe)2Zr(OMe)Me, (CpMe)Zr(NMe2)3, (CpEt)Zr(NMe2)3, (CpMe)2Hf(OMe)Me, and CpHf(NMe2)3 (Cp = C5H5, Me = CH3, and Et = C2H5) together with ozone as the oxygen source are thus appropriate precursors for ALD process, providing dense dielectric and insulating films on semiconductor or metallic substrates. Appreciably high conformality (step-coverage) on three-dimensional substrates can be achieved. Since the ability of metastable cubic/tetragonal phases of HfO2 and/or ZrO2 to withstand post-deposition annealing procedures without transformation to lower-permittivity monoclinic phase was a likely issue when fabricating high-density capacitors, the films were further doped or mixed with rare earth metal oxides. In the case of HfO2, quite a recently developed monocyclopentadienyl-based precursor CpHf(NMe2)3 was chosen and used in the experiments devoted to the studies on Y2O3-doped HfO2. In the case of ZrO2, a well-behaving compound (CpMe)2Zr(OMe)Me was chosen for the preparation of ZrO2 films doped or nanolaminated with Gd2O3 and Er2O3. The processes and resulting films examined within the present study may well become considered as those relevant to the fabrication of high-performance capacitor dielectric materials.
Well-controlled atomic layer deposition (ALD) of high-quality thin films of ZrO2 and HfO2 can be realized using novel cyclopentadienyl-based precursors in normal laboratory conditions. Cyclopentadienyls of zirconium and hafnium, viz. (CpMe)2ZrMe2, (CpMe)2Zr(OMe)Me, (CpMe)Zr(NMe2)3, (CpEt)Zr(NMe2)3, (CpMe)2Hf(OMe)Me, and CpHf(NMe2)3 (Cp = C5H5, Me = CH3, and Et = C2H5) together with ozone as the oxygen source are thus appropriate precursors for ALD process, providing dense dielectric and insulating films on semiconductor or metallic substrates. Appreciably high conformality (step-coverage) on three-dimensional substrates can be achieved. Since the ability of metastable cubic/tetragonal phases of HfO2 and/or ZrO2 to withstand post-deposition annealing procedures without transformation to lower-permittivity monoclinic phase was a likely issue when fabricating high-density capacitors, the films were further doped or mixed with rare earth metal oxides. In the case of HfO2, quite a recently developed monocyclopentadienyl-based precursor CpHf(NMe2)3 was chosen and used in the experiments devoted to the studies on Y2O3-doped HfO2. In the case of ZrO2, a well-behaving compound (CpMe)2Zr(OMe)Me was chosen for the preparation of ZrO2 films doped or nanolaminated with Gd2O3 and Er2O3. The processes and resulting films examined within the present study may well become considered as those relevant to the fabrication of high-performance capacitor dielectric materials.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
doktoritööd, füüsika, aatomkihtepitaksia, õhukesed kiled