DETECTION OF METAL CONTAMINANTS ON A SURFACE OF AN AS-CLEANED SEMICONDUCTOR STRUCTURE BASED ON PHOTOLUMINESCENCE MEASUREMENTS

摘要

A method of quality control of cleaning processes for semiconductors such as silicon during device fabrication comprises taking an as-cleaned semiconductor structure following a critical cleaning process step; exposing the surface of the semiconductor structure to at least one high-intensity beam of light from a suitable light source, preferably a laser, and in particular a high-intensity laser, and collecting photoluminescence (PL) produced by excitation of the semiconductor structure by the light beam; making an analysis of the collected photoluminescence signal and using that analysis as the basis for a quality classification of the cleanliness of the semiconductor, in particular by: determining an average photoluminescence intensity emitted across the area of the structure; comparing the average with a predetermined acceptable specification range of photoluminescence; making a quality classification of the cleanliness of the semiconductor structure based thereon, and in particular rejecting or selecting for remedial action such as further cleaning semiconductor structures exhibiting a photoluminescence response outside the said predetermined acceptable specification range. In a preferred embodiment the method is applied as part of a quality control metric during device cleaning and processing. In a refinement of the method a spatially resolved PL map is also collected. An apparatus for performing the method is also described.