Methods for forming semiconductor constructions, and methods for selectively etching silicon nitride relative to conductive material

A method for forming a semiconductor construction, comprising:

• providing a substrate which includes a semiconductor material base, a plurality of electrical nodes supported by the base, a plurality of upwardly-opening containers of conductive material extending upwardly from the nodes, and insulative material between the containers;
• the insulative material including, in ascending order from the base, a first silicon nitride-containing layer, a first sacrificial oxide, a second silicon nitride-containing layer, a second sacrificial oxide, and a third silicon nitride-containing layer;
• forming an opening through the third silicon nitride-containing layer to the second sacrificial oxide;
• removing at least some of the second sacrificial oxide to expose at least a portion of the second silicon nitride-containing layer;
• exposing the conductive material and second silicon nitride-containing layer to an etch which penetrates through the second silicon nitride-containing layer but does not remove at least the majority of the conductive material from the containers;
• the first sacrificial oxide being exposed through the penetrated second silicon nitride-containing layer;
• removing the exposed first sacrificial oxide;
• wherein the conductive material comprises metal;
• wherein only some of the second sacrificial oxide is removed prior to the etch which penetrates through the second silicon nitride-containing layer, leaving a remainder of the second sacrificial oxide;
• and
• wherein said remainder of the second sacrificial oxide is removed during the removal of the first sacrificial oxide.