Auto-stopping slurries for chemical-mechanical polishing of topographic dielectric silicon dioxide
View Patent ↗The present invention provides auto-stopping CMP slurry compositions that minimize post-CMP non-uniformity and also extend the time that polishing can be continued beyond the end point without the risk of over-polishing the dielectric silicon dioxide film. Auto-stopping CMP slurry compositions according to the invention include ceria abrasive particles and an effective amount of a polyalkylamine such as polyethyleneimine dispersed in water. The methods of the invention include polishing a topographic dielectric silicon dioxide film layer using the auto-stopping CMP slurry compositions to obtain a dielectric silicon dioxide surface having a desired predetermined minimum step height.
1. A method for polishing a topographic layer consisting only of dielectric silicon dioxide having areas of up oxide and areas of down oxide, the method comprising:
providing, on both the areas of up oxide and the areas of down oxide, an aqueous slurry composition comprising
from about 0.5% to about 10.0% by weight of ceria abrasive particles, and from about 0.006% to about 0.04% by weight of polyethyleneimine; and
polishing the topographic dielectric silicon dioxide layer using a polishing pad with the aqueous slurry composition disposed therebetween to remove the areas of up oxide and thereby achieve a polished surface consisting only of dielectric silicon dioxide having a predetermined minimum step height of less than about 500 Å;
wherein:
(i) the aqueous slurry composition exhibits auto-stopping behavior once the predetermined minimum step height is achieved;
(ii) the aqueous slurry composition maintains a topography selectivity of at least about 5 or higher for a polishing period that includes over-polishing for twenty-five seconds after the predetermined minimum step height is achieved, where the topography selectivity is expressed as the ratio of the rate at which the areas of up oxide are removed to the rate at which the areas of down oxide are removed during polishing; and
(iii) the aqueous slurry composition maintains an overall polishing efficiency percentage of greater than 90% for the polishing period that includes over-polishing for twenty-five seconds after the predetermined minimum step height is achieved, where the overall polishing efficiency percentage is expressed according to the equation: ((amount of up oxide removed−amount of down oxide removed)/amount of up oxide removed)×100.
2. The method according to claim 1 wherein the predetermined minimum step height is less than about 100 Å.
3. The method according to claim 1 wherein the ceria abrasive particles have a mean volume secondary particle diameter of from about 100 nm to about 175 nm.
4. The method according to claim 1 wherein the polishing step planarizes an inter-layer dielectric layer in an integrated circuit device.
5. The method according to claim 1 wherein the polishing step is a first polishing step in a two-step process of forming a shallow trench isolation structure in an integrated circuit device.
6. A method for polishing a topographic layer consisting only of dielectric silicon dioxide having areas of up oxide and areas of down oxide, the method comprising:
providing, on both the areas of up oxide and the areas of down oxide, an aqueous slurry composition comprising
from about 0.5% to about 10.0% by weight ceria abrasive particles having a mean volume secondary particle diameter of from about 100 nm to about 175 nm, and
from about 0.006% to about 0.04% by weight of a polyethyleneimine having a weight average molecular weight of from about 10,000 to about 25,000; and
polishing the topographic dielectric silicon dioxide layer using a polishing pad with the aqueous slurry composition disposed therebetween to remove the areas of up oxide and thereby achieve a polished surface consisting only of dielectric silicon dioxide having a predetermined minimum step height of less than about 500 Å;
wherein:
(i) the aqueous slurry composition exhibits auto-stopping behavior once the predetermined minimum step height is achieved;
(ii) the aqueous slurry composition maintains a topography selectivity of at least about 5 or higher for a polishing period that includes over-polishing for twenty-five seconds after the predetermined minimum step height is achieved, where the topography selectivity is expressed as the ratio of the rate at which up oxide is removed to the rate at which down oxide is removed during polishing; and
(iii) the aqueous slury composition maintains an overall polishing efficiency percentage of greater than 90% for the polishing period that includes over-polishing for twenty-five seconds after the predetermined minimum step height is achieved, where the overall polishing efficiency percentage is expressed according to the equation: ((amount of up oxide removed−amount of down oxide removed)/amount of up oxide removed)×100.
7. The method according to claim 6 wherein the polishing step planarizes an inter-layer dielectric layer in an integrated circuit device.
8. The method according to claim 6 wherein the predetermined minimum step height is less than about 100 Å.
9. The method according to claim 6 wherein the polishing step is a first polishing step in a two-step process of forming a shallow trench isolation structure in an integrated circuit device.