Chemical mechanical polishing method, and washing/rinsing method associated therewith
View Patent ↗In a chemical mechanical polishing method for polishing a low-k material insulating layer formed on a semiconductor wafer, aqueous abrasive slurry composed of a water component, an abrasive component, a first additive for making the low-k material insulating layer of the semiconductor wafer hydrophilic in nature, and a second additive for adding acidity to the aqueous abrasive slurry, is prepared. The aqueous abrasive slurry is feed to a rotating polishing pad having a larger diameter than that of the semiconductor wafer. The low-k material insulating layer of the semiconductor wafer is applied and pressed onto the rotating polishing pad while rotating the semiconductor wafer in the same rotational direction as that of the rotating polishing pad, whereby a polishing rate of the low-k material insulating layer of the semiconductor wafer is improved.
1. A chemical mechanical polishing method for polishing a low-k material insulating layer formed on a semiconductor wafer, which method comprises:
preparing an aqueous abrasive slurry composed of a water component, an abrasive component, a first additive for making the low-k material insulating layer of said semiconductor wafer hydrophilic in nature, and a second additive for adding acidity to said aqueous abrasive slurry, wherein said low-k material insulating layer is formed as a SiCOH layer or as a methyl silsesquioxane layer;
feeding said aqueous abrasive slurry to a rotating polishing pad; and
applying and pressing the low-k material insulating layer of said semiconductor wafer onto said rotating polishing pad washing said semiconductor wafer, which is drenched with said aqueous abrasive slurry, with an aqueous washing solution; and rinsing the washed semiconductor wafer.
2. A chemical mechanical polishing method as set forth in claim 1 , wherein a pressure at which the low-k material insulating layer of said semiconductor wafer is pressed onto said rotating polishing pad falls within a range between approximately 3 psi and approximately 5 psi.
3. A chemical mechanical polishing method as set forth in claim 1 , wherein said abrasive component comprises 20 wt % colloidal silica.
4. A chemical mechanical polishing method as set forth in claim 1 , wherein said first additive comprises a hydroxide selected from the group consisting of aluminum hydroxide (Al(OH) 3 ) and potassium hydroxide (KOH).
5. A chemical mechanical polishing method as set forth in claim 4 , wherein at most 2 wt % of said hydroxide is contained in said aqueous abrasive slurry.
6. A chemical mechanical polishing method as set forth in claim 1 , wherein an amount of said second additive contained in said aqueous abrasive slurry is determined such that said aqueous abrasive slurry exhibits a pH falling in a range between approximately 3 and approximately 6.
7. A chemical mechanical polishing method as set forth in claim 1 , wherein said low-k material insulating layer exhibits a dielectric constant of at most 3.0.
8. A chemical mechanical polishing method as set forth in claim 1 , further comprising:
rinsing the washed semiconductor wafer with pure water.
9. A chemical mechanical polishing method as set forth in claim 8 , wherein said aqueous washing solution is prepared as an aqueous oxalic acid (C 2 H 2 O 4 ) solution.
10. A chemical mechanical polishing method as set forth in claim 8 , wherein said aqueous washing solution is prepared as an aqueous dilute hydrofluoric acid (DHF) solution.
11. A chemical mechanical polishing method as set forth in claim 1 , wherein said low-k material insulating layer is formed of a material having a methyl radical.
12. A chemical mechanical polishing method as set forth in claim 1 , wherein said semiconductor wafer layer is covered with said low-k material insulating layer.