Conventional memory cells used in binary systems are configured to be selectively switchable between a condition readable as associated with the value “0” and a condition readable as associated with the value “1.” For example, a conductive-bridging random access memory (conductive bridge RAM) cell, also known in the industry as a programmable metallization cell (PMC), is generally configured such that application of a voltage to the cell eventually causes a first and a second electrode of the cell to become short circuited such that the measurable electrical resistance of the cell significantly drops. The short circuit is accomplished by forming a conductive bridge, also known in the industry as a conductive pathway, to electroconductively connect the two electrodes. When no conductive bridge is present, the memory cell has high electrical resistance and may read as “0.” When the conductive bridge electroconductively connects the two electrodes, the resistance of the cell is low, and the memory cell may read as “1.”
The conductive bridge, which is also referred to in the art as a “filament,” is selectively formed or removed by the selective application of voltage to the cell. The conductive bridge generally forms between a negatively-charged electrode and a positively-charged electrode. Therefore, adjusting the voltage applied to the first and second electrodes controls the growth or growth-reversal of the conductive bridge. It is believed that the conductive bridge grows by precipitation of cations (e.g., metal cations) that drift, when under the influence of an applied voltage, through materials separating the first and second electrodes, provided such materials accommodate drift of the cations.
Conventional memory cells, including conductive bridge RAM cells, incorporate multiple components formed from various materials. In forming the materials, sufficient adhesive strength between materials is needed to maintain film stack integrity. If one material to be formed on another material does not exhibit sufficient adhesion with the another material, adhesion enhancement may be needed. For example, a metal-containing material, such as copper, used to form an electrode in a conductive bridge RAM cell may not sufficiently adhere with an overlying cell material, such as a dielectric material. Therefore, forming a conductive bridge RAM cell with sufficient film stack integrity may include enhancement of adhesion between the copper-containing electrode and the cell material. However, conventional methods for enhancing adhesion between materials are not necessarily conducive for use in fabricating memory cells in which atoms drift during operation. For example, conventional adhesion-enhancing films, formed between two materials to increase adhesion between the two materials, may present a barrier to atomic drift. As such, a difficulty of fabricating conductive bridge RAM cells, and other memory cells in which atoms drift between materials during operation, is achieving sufficient adhesion between materials without significantly obstructing drift of atoms between the materials.