Integrated circuit process monitoring and metrology system
View Patent ↗A method for monitoring polishing process parameters for an integrated circuit structure on a substrate. A first metrology site is constructed on the substrate. The first metrology site represents a design extreme of a high density integrated circuit structure. The first metrology site is formed by placing a relatively small horizontal surface area trench within a relatively large surface area field of a polish stop material. A second metrology site is also constructed on the substrate. The second metrology site represents a design extreme of a low density integrated circuit structure. The second metrology site is formed by placing a relatively large horizontal surface area trench within a relatively small surface area field of a polish stop material. The substrate is covered with a layer of an insulating material, thereby at least filling the trenches. A target thickness of the insulating material necessary to leave the trenches substantially filled to a top surface of the field of polish stop material is calculated. The substrate is polished until a first thickness of the insulating material in the trench of the first metrology site is no more than the target thickness. A second thickness of the insulating material in the trench of the second metrology site is measured, and values based on the first thickness and the second thickness are monitored as the polishing process parameters for the integrated circuit structure.
1. A method of monitoring polishing process parameter for an integrated circuit structure on a substrate, the method comprising:
constructing a first metrology site on the substrate, the first metrology site representing a design extreme of a high density integrated circuit structure, the first metrology site formed by placing a relatively small horizontal surface area trench within a relatively large surface area first field of a polish stop material,
constructing a second metrology site on the substrate, the second metrology site representing a design extreme of a low density integrated circuit structure, the second metrology site formed by placing a relatively large horizontal surface area trench within a relatively small surface area second field of the polish stop material, where the first field is a separate field from the second field,
covering the substrate with a layer of an insulating material, thereby at least filling the trenches,
calculating a target thickness of the insulating material necessary to leave the trenches substantially filled to a top surface of the fields of polish stop material,
polishing the substrate until a first thickness of the insulating material in the trench of the first metrology site is no more than the target thickness,
measuring a second thickness of the insulating material in the trench of the second metrology site, and
monitoring values based on the first thickness and the second thickness as the polishing process parameters for the integrated circuit structure.
2. The method of claim 1 further comprising the step of constructing the first metrology site and the second metrology site on scribe lines between the integrated circuits of the substrate.
3. The method of claim 1 further comprising the step of constructing the first metrology site and the second metrology site on intersections of scribe lines between the integrated circuits of the substrate.
4. The method of claim 1 wherein the integrated circuit structure is a shallow trench isolation structure.
5. The method of claim 1 wherein the first metrology site represents a worst case for under polishing and the second metrology site represents a worst case for over polishing.
6. The method of claim 1 wherein the step of polishing further comprises direct chemical mechanical polishing.
7. The method of claim 1 further comprising the step of statistically monitoring a difference between the first thickness and the second thickness.
8. The method of claim 1 further comprising the steps of:
statistically monitoring a difference between the first thickness and the second thickness, and
controlling the polishing process based on the statistical monitoring.