Plasma assisted atomic layer deposition titanium oxide for conformal encapsulation and gapfill applications

摘要

The embodiments herein relate to methods and apparatus for depositing an encapsulation layer over memory stacks in MRAM and PCRAM applications. The encapsulation layer is a titanium dioxide (TiO2) layer deposited through an atomic layer deposition reaction. In some embodiments, the encapsulation layer may be deposited as a bilayer, with an electrically favorable layer formed atop a protective layer. In certain implementations, gaps between neighboring memory stacks may be filled with titanium oxide, for example through an atomic layer deposition reaction or a chemical vapor deposition reaction.

主权项

1. A method of depositing a titanium dioxide encapsulation layer over memory stacks on a semiconductor substrate, comprising:
(a) receiving a substrate having a plurality of magnetoresistive random access memory (MRAM) stacks or phase change random access memory (PCRAM) stacks thereon in a reaction chamber; (b) flowing a titanium-containing reactant into the reaction chamber and allowing the titanium-containing reactant to adsorb onto the surface of the substrate; (c) flowing an oxygen-containing reactant into the reaction chamber and allowing the oxygen-containing reactant to adsorb onto the surface of the substrate; (d) exposing the reaction chamber to plasma for a duration of about 0.5 seconds or less to drive a surface reaction between the titanium-containing reactant and the oxygen-containing reactant to thereby conformally deposit a titanium dioxide encapsulation layer over the plurality of MRAM stacks or PCRAM stacks, wherein the plasma is generated using an RF power density of about 1750 W/m2 or less; (e) repeating (b)-(d) until the encapsulation layer reaches a final thickness; (f) after (e), flowing a second titanium-containing reactant into the reaction chamber and allowing the second titanium-containing reactant to adsorb onto the surface of the substrate; (g) flowing a second oxygen-containing reactant into the reaction chamber and allowing the second oxygen-containing reactant to adsorb onto the surface of the substrate; (h) exposing the reaction chamber to a second plasma to drive a second surface reaction between the second titanium-containing reactant and the second oxygen-containing reactant to thereby conformally deposit a titanium dioxide second encapsulation layer over the encapsulation layer, wherein the second encapsulation layer is deposited under different plasma conditions than the encapsulation layer; and (i) repeating (f)-(h) until the second encapsulation layer reaches a second final thickness.