Tool cleanliness characterization for improving productivity and yields

Tool cleanliness is a prerequisite for increased production ramp, reduced tool down-time and high process yields. Any materials used in the build of material (BOM) must be verified to be clean both in the bulk of the material and on its surface after machining and cleaning. Bulk analyses are destructive due to the nature of the test and the information required. In contrast, surface analyses should be non-destructive so the part may be re-used after surface cleanliness testing or re-cleaned if the test indicates the part does not pass its cleanliness specification. Wafer tool specifications are in place for particles and metals by the original equipment manufacturers (OEMs). Particle specification depends on the method of wafer clamping and wafer metal specification for tool acceptance is typically in the range of 1-5times10¹⁰ atoms/cm². No generally accepted organic specifications are in place. Currently, there are no accepted tool parts particle, metal and organic specifications. Very few machine shops, cleaning houses, OEMs and fabs have developed baseline tool parts cleanliness specifications. This paper describes key analytical techniques for bulk and surface characterization of tool parts.