Process monitoring for gate cut mask
A method of monitoring critical dimensions of gate electrode structures is provided including providing a substrate, forming a gate electrode pattern on the substrate comprising forming gate electrode lines parallel to each other, forming a mask layer on the gate electrode pattern and forming openings in the mask layer in a crosswise direction with respect to the direction of the parallel gate electrode lines, thereby exposing portions of the gate electrode pattern, etching exposed portions of the gate electrode pattern through the mask layer openings, thereby obtaining a negative image of the mask layer openings, removing remaining portions of the mask layer, and monitoring dimensions of the mask layer openings.
1. A method of monitoring critical dimensions of gate electrode structures comprising:
providing a semiconductor substrate;
forming a gate electrode pattern on the substrate comprising forming gate electrode lines parallel to each other;
forming a mask layer on the gate electrode pattern and forming openings in the mask layer, in a crosswise direction with respect to the direction of the parallel gate electrode lines, thereby exposing portions of the gate electrode pattern;
etching exposed portions of the gate electrode pattern through the mask layer openings, thereby obtaining a negative image of the mask layer openings;
removing remaining portions of the mask layer; and
monitoring dimensions of the mask layer openings;
wherein forming the gate electrode pattern comprises forming additional gate electrode shapes in a crosswise direction with regard to the parallel gate electrode lines, the additional gate electrode shapes being geometrically similar to and having a larger area than the mask layer openings such that a predetermined fraction of the mask layer openings completely overlie the additional gate electrode shapes when forming the mask layer openings.
2. The method according to claim 1 , wherein the gate electrode lines have a uniform pitch.
3. The method according to claim 1 , wherein the material of the gate electrode pattern comprises at least one of polysilicon, amorphous silicon, nitrides, oxides, metal silicide or metals.
4. The method according to claim 1 , wherein the material of the mask layer comprises at least one of a photo resist, a planarization layer, an antireflective layer, or a hardmask.
5. The method according to claim 1 , wherein the mask layer covers the entire gate electrode pattern on the substrate.
6. The method according to claim 1 , wherein the predetermined fraction of the mask layer openings which completely overlies the additional gate electrode shapes is between 5%-50%.
7. The method according to claim 6 , wherein the predetermined fraction of mask layer openings is randomly distributed over the gate electrode pattern.
8. The method according to claim 1 , wherein the mask layer openings are at least partially matched to functional SRAM or logic patterns.
9. The method according to claim 1 , wherein each of the additional gate electrode shapes has a substantially rectangular shape with a width in crosswise direction of a multiple of a pitch size and a length in lengthwise direction larger than a corresponding width of the mask layer openings.
10. The method of claim 9 , wherein the corners of the gate electrode shapes are chamfered.
11. The method of claim 1 wherein the step of forming the mask layer on the gate electrode pattern includes lithographic patterning a prepared mask.
12. The method of claim 1 , wherein the step of monitoring dimensions of the mask layer openings includes measurement of the length and the width of the mask layer openings.
13. The method of claim 12 , wherein the step of monitoring dimensions of the mask layer openings further includes comparing the length and the width of the mask layer openings with predetermined values of the length and the width of the mask layer openings.
14. The method of claim 13 , wherein the predetermined values of the length and the width of the mask layer openings correspond to simulated values and/or previously determined values, wherein in case the measured length and width of the mask layer openings are determined to be larger than the simulated values and/or previously determined values, a feedback may be given such that the wafer may be discarded or tools used for processing the wafer are inspected before further processing of other wafers.
15. The method of claim 1 , wherein the step of monitoring dimensions of the mask layer openings further includes measuring tip-to-tip bridging of gate electrode lines.
16. The method of claim 1 , wherein the step of monitoring dimensions of the mask layer openings further includes conducting a scan to provide contamination free manufacturing data to correlate the dimensions of the mask layer openings with tip-to-tip bridging data.
17. The method of claim 1 , wherein the semiconductor substrate is one of a silicon on insulator and fully depleted silicon on insulator substrate.