Method for forming and filling isolation trenches

A method for forming isolation trenches in semiconductor devices, comprising the steps of:

• forming, in a substrate, first trenches having a first width and second trenches having a second width wherein the first width is larger than the second width and the first and second trenches have a same first depth, and wherein the first trenches are formed in a memory array and the second trenches are formed in a support area;
• depositing a masking layer in the first and second trenches, the masking layer including a thickness sufficient to both line the first trenches and completely fill the second trenches;
• exposing a portion of the substrate at a bottom of the first trenches by etching the masking layer to form an opening through the masking layer at the first depth;
• and
• etching the first and second trenches to extend the first trenches to a second depth.

A method for forming isolation trenches in semiconductor devices, comprising the steps:

• providing a semiconductor substrate having a memory array area and a support area formed thereon;
• forming, in the semiconductor substrate, first trenches having a first width in the memory array area and second trenches having a second width in the support area, wherein the first width is larger than the second width and the first and second trenches have a same first depth;
• depositing a masking layer in the first and second trenches, the masking layer including a thickness sufficient to both line the first trenches and completely fill the second trenches;
• exposing a portion of the substrate at a bottom of the first trenches by etching the masking layer to form an opening through the masking layer at the first depth;
• etching the first and second trenches to extend the first trenches to a second depth while maintaining an aspect ratio of the first trenches below a threshold value;
• and
• filling the first trenches to the second depth and the second trenches to the first depth with a dielectric material in a single deposition step.