Reduction in large particle counts in polishing slurries
The present disclosure provides a method for reducing large particle counts (LPCs) in copper chemical mechanical polishing slurry by way of using high purity removal rate enhancer (RRE) in the slurry. The conductivity of the RRE in deionized water solutions correlates very strongly with the number of LPCs in the RRE, and thus in a slurry using the RRE.
1. A method of polishing a semiconductor wafer surface, comprising the step of contacting the wafer surface with a pad and a polishing composition, the polishing composition comprising:
glycine as a removal rate enhancer;
a corrosion inhibitor; and
an abrasive;
wherein the glycine has a conductivity C in deionized water, and wherein the glycine obeys the following inequality:
C≤a*W+b,
wherein W is the wt % of the glycine, based on the total weight of the composition, wherein 0.0005<a<0.0025, and wherein 0.0005<b<0.0025,
wherein W is greater than zero and less than or equal to twenty percent, based on the total weight of the composition,
wherein the composition has a large particle count, wherein the large particle count is defined by the number of particles per milliliter of the composition having a size greater than 0.56 micrometers,
and wherein the conductivity C and the large particle count have a positive correlation, such that the lower the conductivity, the lower the large particle count.
2. The method of claim 1 , wherein the abrasive is selected from the group consisting of alumina, fumed silica, colloidal silica, coated particles, titania, ceria, zirconia, and any mixtures thereof.
3. The method of claim 1 , wherein the polishing composition further comprises an oxidizer selected from the group consisting of hydrogen peroxide, ammonium persulfate, silver nitrate, ferric nitrates, ferric chloride, per acid, per salts, ozone water, potassium ferricyanide, potassium dichromate, potassium iodate, potassium bromate, vanadium trioxide, hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, ferric nitrate, KMnO 4 , other inorganic or organic peroxides, and any mixtures thereof.
4. The method of claim 1 , further comprising an additional ingredient selected from the group consisting of surfactant, biocide, surface finisher, pH adjuster, defect reduction agent, or any mixtures thereof.
5. The method of claim 1 , wherein the conductivity C is less than 0.0525 milliSiemens per centimeter.
6. The method of claim 1 , wherein the corrosion inhibitor is selected from the group consisting of benzotriazole, derivatives of benzotriazole, tolyl triazole, derivatives of tolyl triazole, and any combinations thereof.
7. The method of claim 6 , wherein the conductivity C is less than 0.0525 milliSiemens per centimeter.
8. The method of claim 1 , further comprising the steps of, before the contacting step:
forming the polishing composition from a slurry concentrate by diluting the slurry concentrate with water and an oxidizer,
wherein the slurry concentrate comprises the glycine, the corrosion inhibitor, and the abrasive.
9. The method of claim 8 , wherein the oxidizer is selected from the group consisting of hydrogen peroxide, ammonium persulfate, silver nitrate, ferric nitrates, ferric chloride, per acid, per salts, ozone water, potassium ferricyanide, potassium dichromate, potassium iodate, potassium bromate, vanadium trioxide, hypochlorous acid, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, ferric nitrate, KMnO 4 , other inorganic or organic peroxides, and any mixtures thereof.
10. The method of claim 8 , wherein the slurry concentrate is diluted to a factor of up to 20×.
11. The method of claim 1 , wherein the corrosion inhibitor is an azole.
12. A method of preparing a polishing composition concentrate, the concentrate comprising:
glycine as a removal rate enhancer;
a corrosion inhibitor; and
an abrasive;
wherein the glycine has a conductivity C in deionized water, and the method comprises the step of selecting the glycine so that it obeys the following inequality:
C≤a*W+b,
wherein W is the wt % of the glycine, based on the total weight of the concentrate, wherein 0.0005<a<0.0025, and wherein 0.0005<b<0.0025.
13. The method of claim 12 , wherein W is greater than zero and less than or equal to twenty percent, based on the total weight of the concentrate.
14. The method of claim 12 , wherein the concentrate has a large particle count, wherein the large particle count is defined by the number of particles per milliliter of the concentrate having a size greater than 0.56 micrometers, and wherein the conductivity C and the large particle count have a positive correlation, such that the lower the conductivity, the lower the large particle count.
15. The method of claim 12 , further comprising the step of diluting the concentrate to form a polishing slurry.
16. The method of claim 12 , wherein the corrosion inhibitor is selected from the group consisting of benzotriazole, derivatives of benzotriazole, tolyl triazole, derivatives of tolyl triazole, and any combinations thereof.
17. The method of claim 12 , wherein the corrosion inhibitor is an azole.