A controlled atmosphere polishing ͑CAP͒ system was used to determine the effects of various chamber gases on copper chemical mechanical polishing ͑CMP͒ in the presence and absence of NH 4 OH and H 2 O 2 . Using 500 kPa oxygen or nitrogen has only slight effects on copper removal rates in the presence of 1 wt % H 2 O 2 . Polishing without H 2 O 2 , performed with controlled oxygen partial pressure, demonstrates removal rates that are 4 times higher than using nitrogen. Polishing using inert gases alone demonstrates an oxidant-starved system that reflects little dependence on wafer pressure or velocity. Addition of NH 4 OH ͑pH 10͒ to experiments using oxidizing gases, such as oxygen and air, increases removal rates up to 3ϫ. Removal rates vary linearly with oxygen partial pressure using oxidizing gases for experiments using NH 4 OH at pH 10. A trend indicating a transition from chemical to mechanical control is observed when NH 4 OH concentration is increased at constant oxygen pressure. A copper removal mechanism in the presence of dissolved oxygen has been developed that highlights a buildup of oxidized copper at the wafer surface. The ability to perform CMP in a pressurized gaseous environment has shown that copper removal is a process of mechanical removal, dissolution of abraded material, and copper-oxygen reactions at the wafer surface.

A controlled atmosphere polishing system ͑CAP͒ was used to identify differences in copper chemical mechanical polishing ͑CMP͒ removal characteristics by changing oxygen partial pressure. A two-step kinetic mechanism was proposed, including a copper surface passivation layer formation and subsequent removal. A semiempirical, two-parameter model has been developed to simulate removal rates for multiple wafer pressures, pad-wafer velocities, and oxygen concentrations. The model accurately predicts removal trends with calculated root-mean-square errors of 77-125 A/min. A major advantage of the CAP system is that a point-of-use gaseous oxidant was successfully used to polish copper substrates, and slight changes in oxidant partial pressure were found to significantly affect removal rate trends.

Metallurgy is both an ancient art and a modern science, requiring detailed knowledge of the structure, properties, and behavior of metals and metal alloys. Whereas for many metals, the primary source materials are crude metalliferous ores, for some metals recycled material, ie, scrap, contributes significantly to total metal production. Extractive processes for ores or scrap, which may be physical or chemical and may include treatment for prevention of corrosion, processing of metals or alloys by heat treatment, casting, etc, and physical measurements relating to failure analysis and other structure/property relationships, are all areas of metallurgy. Terms used in metallurgy are defined. The relationship between ore grades, metal prices, and economic feasibility is discussed.

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The article contains sections titled: 1. Introduction 2. Extraction without Chemical Reaction 2.1. General Comments 2.2. Technical Principles and Process Design 2.3. Extraction Processes and Typical Equipment 2.3.1. Batch Extraction 2.3.2. Continuous Extraction 3. Chemical Leaching in Hydrometallurgy 3.1. Methods 3.2. Principles 3.3. Typical Processes and Equipment 3.3.1. Agitation Leaching of an Oxidized Gold Ore 3.3.2. Pressure Leaching of Zinc Sulfide Concentrates 3.3.3. Bioleaching of Refractory Precious‐Metal Concentrates 4. Extraction with Supercritical Fluids 4.1. Principles 4.2. Process Design 4.3. Equipment