Titanium-based high-K dielectric films
This disclosure provides (a) methods of making an oxide layer (e.g., a dielectric layer) based on titanium oxide, to suppress the formation of anatase-phase titanium oxide and (b) related devices and structures. A metal-insulator-metal (“MIM”) stack is formed using an ozone pretreatment process of a bottom electrode (or other substrate) followed by an ALD process to form a TiO 2 dielectric, rooted in the use of an amide-containing precursor. Following the ALD process, an oxidizing anneal process is applied in a manner is hot enough to heal defects in the TiO 2 dielectric and reduce interface states between TiO 2 and electrode; the anneal temperature is selected so as to not be so hot as to disrupt BEL surface roughness. Further process variants may include doping the titanium oxide, pedestal heating during the ALD process to 275-300 degrees Celsius, use of platinum or ruthenium for the BEL, and plural reagent pulses of ozone for each ALD process cycle. The process provides high deposition rates, and the resulting MIM structure has substantially no x-ray diffraction peaks associated with anatase-phase titanium oxide.
1. A method of forming a capacitor stack, the method comprising:
forming an electrode on a substrate;
pretreating a surface of the electrode with an oxidizer;
forming a dielectric layer above the surface of the electrode using an ALD process, the dielectric layer including a titanium oxide with a dopant metal oxide included therein, where the ALD process comprises using an amide-containing titanium precursor and an oxygen source reagent to form the titanium oxide, annealing at least the dielectric layer; and
forming a second electrode above the dielectric layer;
wherein dopant metal oxide is yttrium oxide;
the method further comprising the introduction of a yttrium precursor during the ALD process;
wherein the yttrium precursor is introduced as a separate step in the ALD deposition process than the introduction of the amide-containing titanium precursor step; and
wherein the yttrium oxide is present in an amount of between about 1% and about 2%.
2. The method of claim 1 wherein the yttrium precursor is selected from the group of diketonate-based yttrium material or a cyclopentadienyl (Cp)-based yttrium material.
3. The method of claim 1 wherein the amide-containing titanium precursor is selected form the group consisting of tetrakis dimethylamino titanium (TDMAT), tetrakis (diethylamino) titanium (TDEAT), or tetrakis (ethylmethylamino) titanium (TEMAT).