Marcus Schumacher

Deposition of hafnium silicate films by liquid injection MOCVD using a single source or dual source approach

Two approaches have been investigated for the MOCVD of high-κ hafnium silicate (HfSixOy) films for gate dielectric applications. The first approach using the novel “single source” precursor [Hf(OSiButMe2)4(Et2NH)], gave a level of Si (∼10 at%) which showed little variation over a range of growth temperatures and oxygen partial pressures. The second, more flexible approach, uses two separate Hf and Si sources, Hf(NMe2)4 and ButMe2SiOH, and allows good control of the Si concentration in HfSixOy, depending on the relative precursor ratios, up to a maximum level of 18 at%. The dielectric properties of the HfSixOy films deposited by this method were shown to be very good. In the dual source process it is proposed that an intermediate containing direct Hf–OSiButMe2 bonds is formed in situ in the gas phase. The crystal structure of [Hf(OSiButMe2)4(Et2NH)] is also reported.

Electrical Characterization of Capacitors with AVD-Deposited Hafnium Silicates as High-k Gate Dielectric

We discuss the electrical properties of hafnium silicates with various composition deposited by atomic vapor deposition (AVD) as metal-oxide-semiconductor (MOS) capacitors. The deposited layers demonstrate well-behaved capacitance as function of gate voltage (CV) curves with a leakage as low as 5×10 - 2 for an equivalent oxide thickness (EOT) of 1.3 nm. The permittivity (k-value) ranges from 6 to 14 depending on the composition of the hafnium silicate. Flatband voltage depends on the composition (and thickness) and varies between -0.10 and 0.45 V, from which we calculated the amount of net charge in the layer, between (-6 ′ 3)×10 1 1 and (20 ′ 3) X 10 1 1 /cm 2 . Postdeposition treatments at 800°C in O 2 or NH 3 shift the V F B position up to 100 mV, together with a change of the amount of net charge. Fine-tuning the deposition and composition might nullify the net charge contribution in the layers.

Controlled metal-organic chemical vapor deposition of ferroelectric thin films

The metal-organic chemical vapor deposition (MOCVD) of ferroelectric thin films is being widely investigated for the manufacture of devices requiring both volatile and non-volatile memory. The consistent deposition of multicomponent thin films with uniform characteristics requires superior hardware engineering to control a large number of variables. Well known for its success in engineering III-V multicomponent thin film reactors, AIXTRON has combined liquid delivery system and showerhead designs with its established knowledge of temperature and pressure control for the deposition of strontium bismuth tantalate (SBT) and other ferroelectric chemistries. Among the important aspects of SBT MOCVD to be studied are the control of Sr and Ta incorporation and conformal coverage. Data on these two aspects of SBT thin film deposition are reported here.