mode by the design of heteroleptic ligand system around the central Ti ion.
This solution allows- The highest deposition rate reported to date (1.07 Å.cycle-1
) which is 6 times
higher than the current standard, increasing the general throughput.
The highest ALD window reported to date (up to 390°C), allowing easier formation of the desired crystalline phase
Excellent electrical properties: an Equivalent Oxide Thickness (EOT) of 5.7 Å and a low leakage current density of (~2 x 10-8
Efficient control of Sr:Ti ratio in the deposited STO film, allowing ease of tunability in composition.
Ruthenium based material, such as Ru, RuO2 SRO (SrRuO3
) are under consideration as
effective electrode materials for use in advanced memory stacks, because of their superior characteristics, such as high melting point, high oxidation resistance and high work function. Specifically when used as an electrode with STO dielectrics, the STO films can be epitaxially grown on top of the Ru film to initiate and achieve in-situ crystallization that provides higher k material form.
The high cost of ownership associated with conventional organometallic ruthenium precursor had significantly impeded the adoption of this element in high volume manufacturing. Recognizing this challenge, Air Liquide has introduced ToRuS, which is based on a carefully tuned proprietary formulation containing an inorganic ruthenium compound in a tailored solvent mixture. Its relatively high vapor pressure (10 Torr at
25°C) compared to other commonly available ruthenium precursors, allows high deposition rates without the need for canister or line heating. ToRuS has been successfully demonstrated to yield excellent quality ruthenium thin films by CVD and ALD with high deposition rates (1.8 Å/cycle by ALD) and good adhesion characteristics on a variety of substrates (Si, SiO2 HfO2
, SiN, SiC, Al2 ,and La2 O3 ). These superior characteristics have lead to O3 , Ta2 O5 , TaN, ,
its rapid adoption in the manufacture of GMR (Giant Magneto-Resistive) based sensors in the hard disk industry, and it is now being actively investigated for electrode applications in the semiconductor industry.
As memory device makers expand their quest for a “universal memory” that integrates the advantages of various memory technologies, the need for enabling materials will continue to be increasingly important.
While a clear winner is yet to be determined, Phase Change Memories (PCM/PCRAM), which are based on resistivity changes associated with thermally reversible changes in the crystal structure of chalcogenide glass (Gex
Sby Tez ), have shown promise. Novel
precursors that allow efficient deposition of high quality GST films continue to fuel the development efforts on the roadmap for memory devices.
Composition of STO films evaluated by XPS as function of the ratio of alternating cycles of two Sr & Ti precursors
Process advantage of ToRuS vs. conventional organometallic Ru precursor (DER). Note small grain size even after Rapid Thermal Annealing
Issue IV 2010
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