Forming air gaps in memory arrays and memory arrays with air gaps thus formed

A method of forming a memory array, comprising:

• forming a first dielectric over a semiconductor;
• forming a charge-storage material over the first dielectric;
• forming an isolation region, comprising a second dielectric, through the first dielectric and the charge-storage material, and extending into the semiconductor;
• forming an access-line stack over the isolation region;
• forming protective sidewall spacers on side surfaces of the access-line stack that extend into the second dielectric;
• and
• removing the second dielectric between the protective sidewall spacers, leaving a thickness of the second dielectric vertically under the access-line stack between the protective sidewall spacers, so as to form an air gap in the isolation region that passes through the charge-storage material and that is between the thickness of the second dielectric and the semiconductor.

A method of forming a memory array, comprising:

• forming an isolation region extending into a semiconductor;
• forming a plurality of access-line stacks and select-line stacks over the isolation region;
• forming a protective liner in first openings between adjacent access-line stacks and in a second opening between adjacent select-line stacks;
• forming a mask over the protective liner in the second opening;
• anisotropically removing the protective liner from the bottoms of the first openings, leaving a portion of the protective liner on sides of the first openings and exposing a dielectric in the isolation region at the bottoms of the first openings;
• removing the mask;
• isotropically removing the dielectric exposed at the bottoms of the first openings so as to form a third opening in the dielectric that extends under the access-line stacks;
• and
• forming a material in the first openings and the second opening so that the material closes off the first openings;
• wherein the closed off first openings and the third opening are contiguous and form an air gap in the isolation region.

A method of forming a memory array, comprising:

• forming an isolation region extending into a semiconductor;
• forming a plurality of access-line stacks and select-line stacks over the isolation region;
• forming a first thickness of protective material in first openings between adjacent access-line stacks and in a second opening between adjacent select-line stacks;
• forming a mask over the first thickness of protective material in the second opening;
• while using the mask to prevent the first thickness of protective material in the second opening from being removed, anisotropically removing the first thickness of protective material from the bottoms of the first openings to form sidewall spacers of the first thickness of protective material on sides of the first openings and to expose a thickness of a dielectric of the isolation region at bottoms of the first openings;
• while using the mask to prevent the first thickness of protective material in the second opening from being removed, anisotropically removing the exposed thickness of the dielectric of the isolation region to form extended first openings that extend into the dielectric of the isolation region below lower ends of the sidewall spacers of the first thickness of protective material and that expose the dielectric of the isolation region below the lower ends of the sidewall spacers of the first thickness of protective material;
• removing the mask;
• forming a second thickness of protective material over the first thickness of protective material in the second opening, on the sidewall spacers of the first thickness of protective material in the extended first openings, and over the exposed dielectric of the isolation region below the lower ends of the sidewall spacers of the first thickness of protective material in the extended first openings;
• anisotropically removing the second thickness of protective material from the bottoms of the extended first openings to expose the dielectric of the isolation region at the bottoms of the extended first openings and to form extended sidewall spacers of the second thickness of protective material in the first openings over the sidewall spacers of the first thickness of protective material and extending below the lower ends of the sidewall spacers of the first thickness of protective material;
• isotropically removing the dielectric of the isolation region exposed at the bottoms of the extended first openings so as to form a third opening in the dielectric of the isolation region that extends under the access-line stacks;
• and
• forming a material in the extended first openings and the second opening so that the material closes off the extended first openings;
• wherein the closed off extended first openings and the third opening are contiguous and form an air gap in the isolation region.