Methods of forming trench isolation and methods of forming floating gate transistors

1. A method of forming trench isolation, comprising:

forming mask lines over a semiconductor substrate;

forming sidewall spacers laterally over sidewalls of the mask lines, the sidewall spacers respectively having a first sidewall spacer edge in physical touching contact with one of the sidewalls of the mask lines and a second sidewall spacer edge opposite the first sidewall spacer edge, the second sidewall spacer edge not being in physical touching contact with any sidewall of the mask lines;

etching first trench lines into semiconductive material of the semiconductor substrate between the sidewall spacers using the mask lines and sidewall spacers as a first etching mask;

depositing first isolation material to within and overfilling the first trench lines within the semiconductive material to be received between adjacent of the sidewall spacers and to be received elevationally over the mask lines and sidewall spacers, the second sidewall spacer edge being in physical touching contact with the first isolation material;

removing the first isolation material effective to expose the mask lines;

after the removing, etching the mask lines from the substrate selectively relative to the sidewall spacers;

after etching the mask lines from the substrate, etching second trench lines into semiconductive material of the semiconductor substrate using the sidewall spacers and the first isolation material within the first trench lines as a second etching mask, the second sidewall spacer edge being in physical touching contact with the first isolation material during the etching of the second trench lines into the semiconductive material, the first sidewall spacer edge being laterally exposed during the etching of the second trench lines into the semiconductive material;

depositing second isolation material to within and overfilling the second trench lines within the semiconductive material; and

removing the sidewall spacers from the substrate after the etching of the second trench lines into the semiconductive material.

2. The method of claim 1 comprising removing the sidewall spacers from the substrate after depositing the second isolation material.

3. The method of claim 1 comprising removing the overfilled second isolation material and the overfilled first isolation material back at least to the semiconductive material.

4. The method of claim 3 comprising removing the sidewall spacers from the substrate after depositing the second isolation material; the removing of the overfilled second isolation material, the overfilled first isolation material, and the sidewall spacers comprising polishing.

5. The method of claim 1 wherein the first trench lines are etched to a uniform depth within the semiconductive material, and the second trench lines are etched to a uniform depth within the semiconductive material which is the same as the uniform depth of the first trench lines within the semiconductive material.

6. A method of forming floating gate transistors, comprising:

forming floating gate material over first gate dielectric material over semiconductive material of a semiconductor substrate;

forming mask lines over the floating gate material;

forming sidewall spacers laterally over sidewalls of the mask lines, the sidewall spacers respectively having a first sidewall spacer edge in physical touching contact with one of the sidewalls of the mask lines and a second sidewall spacer edge opposite the first sidewall spacer edge, the second sidewall spacer edge not being in physical touching contact with any sidewall of the mask lines;

etching first trench lines into the floating gate material, the first gate dielectric material, and the semiconductive material of the semiconductor substrate between the sidewall spacers using the mask lines and sidewall spacers as a first etching mask;

forming first isolation material within the first trench lines within the semiconductive material, the second sidewall spacer edge being in physical touching contact with the first isolation material;

after forming the first isolation material within the first trench lines, etching the mask lines from the substrate selectively relative to the sidewall spacers;

after etching the mask lines from the substrate, etching second trench lines into the floating gate material, the gate first dielectric material, and the semiconductive material of the semiconductor substrate using the sidewall spacers and the first isolation material within the first trench lines as a second etching mask, the second sidewall spacer edge being in physical touching contact with the first isolation material during the etching of the second trench lines into the semiconductive material, the first sidewall spacer edge being laterally exposed during the etching of the second trench lines into the semiconductive material;

forming second isolation material within the second trench lines within the semiconductive material; and

after forming the second isolation material with the second trench lines, forming second gate dielectric material over the floating gate material and forming control gate material over the second gate dielectric material.

7. The method of claim 6 comprising removing the sidewall spacers from the substrate at a point in time after etching the second trench lines.

8. The method of claim 7 wherein the point in time is also after forming the second isolation material within the second trench lines.

9. The method of claim 6 wherein forming the first isolation material within the first trench lines overfills the first trench lines, and forming the second isolation material within the second trench lines overfills the second trench lines; and further comprising removing the first isolation material, the second isolation material, and the spacers by polishing or etching at least to the semiconductive material of the substrate.

10. The method of claim 6 wherein the first trench lines are etched to a uniform depth within the semiconductive material, and the second trench lines are etched to a uniform depth within the semiconductive material which is the same as the uniform depth of the first trench lines within the semiconductive material.

11. A method of forming floating gate transistors, comprising:

forming floating gate material over first gate dielectric material over semiconductive material of a semiconductor substrate;

forming mask lines over the floating gate material;

forming sidewall spacers on sidewalls of the mask lines;

etching first trench lines into the floating gate material, the first gate dielectric material, and the semiconductive material of the semiconductor substrate between the sidewall spacers using the mask lines and sidewall spacers as a first etching mask, the first trench lines being etched to a uniform depth within the semiconductive material;

forming first isolation material within the first trench lines within the semiconductive material;

after forming the first isolation material within the first trench lines, etching the mask lines from the substrate selectively relative to the sidewall spacers;

after etching the mask lines from the substrate, etching second trench lines into the floating gate material, the gate first dielectric material, and the semiconductive material of the semiconductor substrate using the sidewall spacers and the first isolation material within the first trench lines as a second etching mask, the second trench lines being etched to a uniform depth within the semiconductive material which is the same as the uniform depth of the first trench lines within the semiconductive material;

forming second isolation material within the second trench lines within the semiconductive material;

the forming of the first isolation material within the first trench lines overfilling the first trench lines, and the forming of the second isolation material within the second trench lines overfilling the second trench lines;

removing the first isolation material and the second isolation material by polishing or etching to form the first isolation material, the second isolation material, and the floating gate material to have respective elevationally outermost surfaces which are coplanar relative to one another;

removing all of the sidewall spacers from the substrate; and

after the removing of the first isolation material and the second isolation material, forming second gate dielectric material over the floating gate material and forming control gate material over the second gate dielectric material.

12. The method of claim 11 wherein the sidewall spacers are removed after forming the second isolation material.

13. The method of claim 12 wherein the sidewall spacers are removed during said removing of the first isolation material and the second isolation material by polishing or etching.

14. The method of claim 11 wherein said removing of the first isolation material, the second isolation material, and the sidewall spacers is by polishing.

15. The method of claim 11 wherein said removing of the first isolation material, the second isolation material, and the sidewall spacers is by polishing.

16. The method of claim 11 wherein the etching of the second trench lines forms the floating gate material, the first gate dielectric material, and the semiconductive material between adjacent first and second trench lines to have respective minimum widths which are no greater than 35 nanometers.

17. The method of claim 11 wherein the first trench lines have respective maximum open widths within the floating gate material, the first gate dielectric material, and the semiconductive material between adjacent first trench lines; the etching of the first trench lines forming the floating gate material, the first gate dielectric material, and the semiconductive material between adjacent first trench lines to have respective minimum widths which are about twice that of said respective maximum open widths of the first trench lines.

18. The method of claim 17 wherein the respective minimum widths are no greater than 35 nanometers.