CHEMICAL MECHANICAL POLISHING ENDPOINT DETECTION

摘要

The present invention provides apparatus and methods for detecting removal of a material in a chemical mechanical polishing process that uses a solution (110) and operates upon a top layer (16) made of a material that is disposed over another layer on a multi-layer workpiece (114). When the top layer from the workpiece is removed using chemical mechanical polishing with the solution, a flow of used solution results, with the flow of used solution containing therein the material removed from the top layer. While removing the top layer, a beam of light is transmitted on the flow of used solution to obtain an output beam of light that is altered due to absorption by the material, and a change in a characteristic of the output beam of light (124) from the beam of light (120) indicative of a change in a n amount of the material within the flow of used solution is detected.