1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more specifically, to a method of manufacturing a semiconductor device, which includes a polishing treatment using a CMP (chemical mechanical polishing) slurry.
2. Description of the Related Art
For manufacturing ultra-large scale integrated circuits, there is a recent trend of increasing the packaging or mounting density by reducing the size of transistors and other semiconductor elements. To this end, various fine processing techniques have been studied and developed, and according to the current design rules, the downsizing of elements has made such a progress to achieve sub-micron orders.
One of the techniques that have been developed to satisfy such tight downsizing demands is the CMP technique. This technique is an indispensable technique for, for example, the formation of buried metal wires, the planarization of interlayer insulating films, and the formation of connection plugs, buried isolations and buried capacitors in the manufacture of a semiconductor device.
In the CMP technique, a CMP slurry containing polishing grains is supplied on the surface of a semiconductor wafer and the surface of the wafer is slid on a polishing pad while the wafer surface is pressed against the pad, thereby chemically and mechanically polishing the wafer surface. For example, recesses (such as wiring grooves, via holes or contact holes) are formed in an insulating film formed on a semiconductor substrate. A metallic material layer is formed, filling the recesses and covering the surface of the insulating film, and then the metallic material layer is removed by the CMP until the underlying insulating film is exposed. In this manner, an electrically conductive layers (such as wiring layers or plugs) can be formed which remain (or are buried) in the recess portion. In this case, excessive polishing is required in order to avoid remnants of the metallic material after the polishing, which are caused by the in-plain or wafer-to-wafer variations in the rate of polishing by the CMP slurry. However, the excessive polishing creates dishing or erosion. The dishing or erosion may cause failure such as short-circuiting between wirings formed later.
To suppress dishing or erosion, U.S. Pat. No. 6,316,366 B1 discloses a CMP slurry which contains abrasive grains, two types of special oxidizing agents (urea hydrogen peroxide and dipersulfate or monopersulfate), and optionally an organic acid. This CMP slurry is used to polish a multi-layered metal in one step. Jpn. Pat. Appln. KOKAI Publication No. 2003-77919 discloses, in forming buried metallic wirings, removing a conductive material layer with a first polishing slurry halfway on one polishing platen (station), and then polishing the remaining conductive material layer with a second polishing slurry on another polishing platen until the underlying barrier film is exposed. Finally, the conductive material layer and the barrier layer are polished on still another polishing platen until the insulating film is exposed. The KOKAI Publication No. 2003-77919 discloses an aqueous slurry of colloidal silica or fumed silica, containing glycin or citric acid, and benzotriazole (BTA) and hydrogen peroxide, as a polishing slurry which can suppress erosion or dishing.