Improvement of dielectric properties of SrxZr(1-x)Oy grown by molecular beam deposition and sputtering

Following the demand of replacing conventional dielectrics in the semiconductor industry, a material screening for new high-k dielectrics with nanometer-scale thicknesses is required. Among the many investigated potential materials are ZrO2 as well as laminates and mixtures of ZrO2 with HfO2, Ta2O5 and Al2O3. We concentrated our efforts to the growth and characterisation of ZrO2 with the admixture of SrO to form SrxZr(1-x)Oy. We employed the molecular beam deposition technique (MBD) in a co-deposition regime for this purpose. The capability of MBD for high-k material screening was verified by comparison to deposition via sputtering a stoichiometric SrZrO3 target. The investigated test structures were metal-insulator-metal capacitors (MIM) with a TiN bottom electrode on n++-Si substrates. I-V and C-V measurements revealed a k-value of 19 for amorphous SrxZr(1-x)Oy grown by either MBD or sputtering. After surpassing a crystallisation temperature of approximately 650 C the k-value increases to 30 while the dielectric changes into a polycrystalline film with a cubic phase. A comparison of MBD and sputtering of ZrO2 and SrxZr(1-x)Oy will be presented in detail.