DIALKYLDITELLURIDES (DITELLURIUM DIALKYLS)

Fig. Molecular structure (single crystal XRD) of Te2(tBu2)

      Dialkylditellurides, including dimethyl ditelluride Te2Me2, diethyl ditelluride Te2Et2, diisopropyl ditelluride Te2iPr2, and di-tertiary-butyl ditelluride Te2(tBu)2, were proposed as potential precursors for the CVD and ALD growth of Te-containing materials at low temperatures, f.e. Sb2Te3 films for the formation of GST films in phase change memory applications. For such applications, the tellurium precursor used for forming GST films should have the ability to deposit at sufficiently low temperature to achieve amorphous Sb2Te3 films with good step coverage (crystalline films do not provide the necessary step coverage for phase change memory device applications). Dialkyl tellurides conventionally used to deposit Te-containing films by CVD or ALD in phase change memory applications usually require relatively high temperatures for film deposition. This issue can be potentially resolved by use of dialkyl ditellurides, f.e. di-tertbutyl ditelluride, Te2(t-Bu)2.

Di-tert-butyl-ditelluride Te2tBu2

Fig. STA ( simultaneous TGA-DSC) plot of Te2(tBu)2

    The reason for the lower deposition temperature achievable by using dialkyl ditellurides is a relatively weak Te-Te bond. Thus, in Te2(t-Bu)2 a fairly long Te—Te bond of 2.68 A was found by single-crystal X-ray study (see Fig. is an ORTEP diagram of the molecular structure of Te2(t-Bu)2)

   The potentially achievable lower deposition temperature is confirmed by simultaneous thermal analysis (STA) of Te2(t-Bu)2, which shows a very low T50 of 146° C. (see Fig.  is a simultaneous thermal analysis (STA) plot of thermogravimetry (TG) and differential scanning calorimetry (DSC) data for Te2(t-Bu)2.) [i]

       Synthesis and characterisation of Te2(t-Bu)2 is described in the literature [ii], [iii],[iv]

[i] M Stender, C Xu, T. Chen, W. Hunks, Ph.S.H. Chen, J.F. Roeder, Th.H. Baum, US Pat. US8796068B2 / 2014« TELLURIUM COMPOUNDS USEFUL FOR DEPOSITION OF TELLURIUM CONTAINING MATERIALS « , https://patents.google.com/patent/US8796068B2/en

[ii] C. H. W. Jones, R. D. Sharma, J. of Organomet. Chem. 1983, 255, 61-70

[iii] R. W. Gedridge Jr., K. T. Higa, R. A. Nissan, Organometallics 1991, 10, 286-291

[iv] U.S. Pat. No. 5,166, 428

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