Method for forming conductors and their contacts which carry signals for advanced semiconductor memory devices with self-aligned sti support beams

A method for forming conductors and their contacts which carry signals for advanced semiconductor memory device with self-aligned STI support beams, comprising:

• providing a silicon substrate;
• forming a first dielectric layer on the silicon substrate;
• forming a first patterning layer on the first dielectric layer, wherein the first patterning layer comprises a sub shallow trench isolation pattern in a first direction and a sub support beam pattern in a second direction perpendicular to the first direction;
• etching the first dielectric layer unprotected by the first patterning layer to exposed the silicon substrate;
• removing the first patterning layer such that a patterning first dielectric layer are provided, wherein the patterning first dielectric layer comprises the sub shallow trench isolation pattern and the sub support beam pattern;
• performing a first STI etching in a way that an anisotropic STI silicon etching is executed in the second direction and a STI tilt silicon etching is executed in the first direction simultaneously, whereby a plurality of first shallow trench in the second direction is provided and part of the silicon substrate underneath the sub support beam pattern is removed to leave a plurality of silicon support beams hanging underneath the sub support beam pattern inside the first shallow trenches and adjoining the silicon substrate underneath the sub shallow trench isolation pattern;
• performing a first thermal oxidation process such that a first silicon dioxide liner layer is formed along each of the first shallow trenches and the silicon support beams are self-transformed to silicon dioxide support beams in the first shallow trenches;
• forming a layer of first conductor on the patterning first dielectric layer and performing a first chemical mechanical polish process to stop on the patterning first dielectric layer to have the first conductor filling the first shallow trenches;
• removing part of the first conductor filled in the first shallow trenches to form a plurality of first signal-carrying conductor and first conductor pillars integrated with the plurality of first signal-carrying conductor, wherein the first conductor pillars are underneath the silicon dioxide support beams and to be electrically connect contacts of the plurality of first signal-carrying conductor;
• performing a first silicon dioxide deposition process to have the first signal-carrying conductor and first conductor pillars buried in the first shallow trenches filled with silicon dioxide;
• and
• performing a second chemical mechanical polish process to form a first shallow trench isolation structure.