LOCOS trench isolation structures

An isolation structure comprising:

• a semiconductor substrate having a first active region and a separate second active region each of the first and second active regions extending to a top surface of the semiconductor substrate;
• a field oxide region having a convex top surface opposite a convex bottom surface, wherein the convex bottom surface extends within the semiconductor substrate below the top surface of the semiconductor substrate to a first depth, the field oxide region is separated from the first and second separate active regions, and the convex top surface extends above the top surface of the semiconductor substrate;
• a first isolation trench extending into the semiconductor substrate, the first isolation trench filled with a dielectric material comprising a nitride, and having a first spacer formed thereto, the first spacer extending above the top surface of the semiconductor substrate, wherein:
• the first isolation trench has first and second opposite sides;
• the first side of the first isolation trench in contact with the field oxide region;
• and
• the second side of the first isolation trench in contact with the first active region;
• and
• a second isolation trench extending into the semiconductor substrate, the second isolation trench filled with a dielectric material comprising a nitride and having a second spacer formed thereto, the second spacer extending above the top surface of the semiconductor substrate, wherein:
• the second isolation trench has first and second opposite sides;
• the first side of the second isolation trench in contact with the field oxide region;
• and
• the second side of the second isolation trench in contact with the second active region.

An isolation structure, comprising:

• a semiconductor substrate comprising a semiconductive material and having first and second separate active regions each extending to a top surface of the semiconductor substrate;
• a field oxide region having a curved top surface and an opposite curved bottom surface, wherein:
• the curved bottom surface projects within the semiconductor substrate below the top surface of the semiconductor substrate;
• the field oxide region is separated from the first and second separate active regions;
• and
• the curved top surface projects above the top surface of the semiconductor substrate;
• a pair of nitride dielectric extensions each:
• having opposite first and second sides;
• projecting within and in contact with the semiconductive material of the semiconductor substrate below the top surface of the semiconductor substrate;
• contacting a respective active region on the first side thereof;
• being out of contact from one of an active region on the second side thereof;
• and
• projecting above the top surface of the semiconductor substrate;
• and
• a pair of layers each of which:
• is upon a respective one of the active regions;
• and
• intersects a respective one of the dielectric extensions on one of the opposite sides of the field oxide region;
• wherein each of the dielectric extensions constitutes a structural barrier between the opposite first and second sides, configured to prevent the contact with a respective one of the active regions and the field oxide region, and configured to prevent the encroachment of material from the field oxide region into the respective active region.

An isolation structure including a semiconductor substrate having a plurality of active regions and a top surface of the semiconductor substrate, the isolation structure comprising:

• a pair of dielectric trench structures each of which:
• including a top portion comprising a nitride upon a bottom portion comprising an oxide;
• in contact with one of the active regions;
• extending below the top surface of the semiconductor substrate to a first depth;
• and
• extending above the top surface of the semiconductor substrate to a first height;
• a field oxide region extending into the semiconductor substrate to a second depth less than the first depth, wherein the field oxide region:
• extends above the top surface of the semiconductor substrate to a second height;
• is physically separate from the plurality of active regions;
• is longer than it is high;
• and
• has opposite sides each of which makes contact with the nitride of a respective one of the dielectric trench structures;
• and
• oxide layers upon each of the active regions and making contact with the field oxide region.